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Narsil MCP

Rust MCP server for comprehensive code intelligence - 90 tools, 32 languages, security scanning, call graphs, and more

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narsil-mcp

The blazing-fast, privacy-first MCP server for deep code intelligence

A Rust-powered MCP (Model Context Protocol) server providing AI assistants with deep code understanding through 90 specialized tools.

Why narsil-mcp?

Feature	narsil-mcp	XRAY	Serena	GitHub MCP
Languages	32	4	30+ (LSP)	N/A
Neural Search	Yes	No	No	No
Taint Analysis	Yes	No	No	No
SBOM/Licenses	Yes	No	No	Partial
Offline/Local	Yes	Yes	Yes	No
WASM/Browser	Yes	No	No	No
Call Graphs	Yes	Partial	No	No
Type Inference	Yes	No	No	No

Key Features

Code Intelligence - Symbol extraction, semantic search, call graph analysis
Neural Semantic Search - Find similar code using embeddings (Voyage AI, OpenAI)
Security Analysis - Taint analysis, vulnerability scanning, OWASP/CWE coverage
Supply Chain Security - SBOM generation, dependency auditing, license compliance
Advanced Analysis - Control flow graphs, data flow analysis, dead code detection

Why Choose narsil-mcp?

Written in Rust - Blazingly fast, memory-safe, single binary (~30MB)
Tree-sitter powered - Accurate, incremental parsing for 32 languages
Zero config - Point at repos and go
MCP compliant - Works with Claude, Cursor, VS Code Copilot, Zed, and any MCP client
Privacy-first - Fully local, no data leaves your machine
Parallel indexing - Uses all cores via Rayon
Smart excerpts - Expands to complete syntactic scopes
Security-first - Built-in vulnerability detection and taint analysis
Neural embeddings - Optional semantic search with Voyage AI or OpenAI
WASM support - Run in browser with WebAssembly build
Real-time streaming - Results as indexing progresses for large repos

Supported Languages

Language	Extensions	Symbols Extracted
Rust	`.rs`	functions, structs, enums, traits, impls, mods
Python	`.py`, `.pyi`	functions, classes
JavaScript	`.js`, `.jsx`, `.mjs`	functions, classes, methods, variables
TypeScript	`.ts`, `.tsx`	functions, classes, interfaces, types, enums
Go	`.go`	functions, methods, types
C	`.c`, `.h`	functions, structs, enums, typedefs
C++	`.cpp`, `.cc`, `.hpp`	functions, classes, structs, namespaces
Java	`.java`	methods, classes, interfaces, enums
C#	`.cs`	methods, classes, interfaces, structs, enums, delegates, namespaces
Bash	`.sh`, `.bash`, `.zsh`	functions, variables
Ruby	`.rb`, `.rake`, `.gemspec`	methods, classes, modules
Kotlin	`.kt`, `.kts`	functions, classes, objects, interfaces
PHP	`.php`, `.phtml`	functions, methods, classes, interfaces, traits
Swift	`.swift`	classes, structs, enums, protocols, functions
Verilog/SystemVerilog	`.v`, `.vh`, `.sv`, `.svh`	modules, tasks, functions, interfaces, classes
Scala	`.scala`, `.sc`	classes, objects, traits, functions, vals
Lua	`.lua`	functions, methods
Haskell	`.hs`, `.lhs`	functions, data types, type classes
Elixir	`.ex`, `.exs`	modules, functions
Clojure	`.clj`, `.cljs`, `.cljc`, `.edn`	lists (basic AST)
Dart	`.dart`	functions, classes, methods
Julia	`.jl`	functions, modules, structs
R	`.R`, `.r`, `.Rmd`	functions
Perl	`.pl`, `.pm`, `.t`	functions, packages
Zig	`.zig`	functions, variables
Erlang	`.erl`, `.hrl`	functions, modules, records
Elm	`.elm`	functions, types
Fortran	`.f90`, `.f95`, `.f03`, `.f08`	programs, subroutines, functions, modules
PowerShell	`.ps1`, `.psm1`, `.psd1`	functions, classes, enums
Nix	`.nix`	bindings
Groovy	`.groovy`, `.gradle`	methods, classes, interfaces, enums, functions

Installation

Via Package Managers (Recommended)

macOS / Linux (Homebrew):

brew tap postrv/narsil
brew install narsil-mcp

Windows (Scoop):

scoop bucket add narsil https://github.com/postrv/scoop-narsil
scoop install narsil-mcp

Arch Linux (AUR):

yay -S narsil-mcp-bin  # Binary release (faster)
# or
yay -S narsil-mcp      # Build from source

Rust/Cargo (all platforms):

cargo install narsil-mcp

Node.js/npm (all platforms):

npm install -g narsil-mcp
# or
yarn global add narsil-mcp
# or
pnpm add -g narsil-mcp

Nix:

# Run directly without installing
nix run github:postrv/narsil-mcp -- --repos ./my-project

# Install to profile
nix profile install github:postrv/narsil-mcp

# With web visualization frontend
nix profile install github:postrv/narsil-mcp#with-frontend

# Development shell
nix develop github:postrv/narsil-mcp

One-Click Install Script

macOS / Linux:

curl -fsSL https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.sh | bash

Windows (PowerShell):

irm https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.ps1 | iex

Windows (Git Bash / MSYS2):

curl -fsSL https://raw.githubusercontent.com/postrv/narsil-mcp/main/install.sh | bash

Note for Windows users: The PowerShell installer provides better error messages and native Windows integration. It will automatically configure your PATH and check for required build tools if building from source.

From Source

Prerequisites:

Rust 1.70 or later
On Windows: Visual Studio Build Tools with "Desktop development with C++"

# Clone and build
git clone git@github.com:postrv/narsil-mcp.git
cd narsil-mcp
cargo build --release

# Binary will be at:
# - macOS/Linux: target/release/narsil-mcp
# - Windows: target/release/narsil-mcp.exe

Feature Builds

narsil-mcp supports different feature sets for different use cases:

# Default build - native MCP server (~30MB)
cargo build --release

# With RDF knowledge graph and CCG tools (~35MB) - SPARQL queries, Code Context Graph
cargo build --release --features graph

# With neural vector search (~32MB) - adds TF-IDF similarity
cargo build --release --features neural

# With ONNX model support (~50MB) - adds local neural embeddings
cargo build --release --features neural-onnx

# With embedded visualization frontend (~31MB)
cargo build --release --features frontend

# Full-featured build with graph + frontend (~40MB)
cargo build --release --features graph,frontend

# For browser/WASM usage
cargo build --release --target wasm32-unknown-unknown --features wasm

Feature	Description	Size
`native` (default)	Full MCP server with all tools	~30MB
`graph`	+ RDF knowledge graph, SPARQL, CCG tools	~35MB
`frontend`	+ Embedded visualization web UI	~31MB
`neural`	+ TF-IDF vector search, API embeddings	~32MB
`neural-onnx`	+ Local ONNX model inference	~50MB
`wasm`	Browser build (no file system, git)	~3MB

Important: The --graph CLI flag requires the binary to be built with --features graph. If you pass --graph to a binary built without this feature, you'll see a warning and SPARQL/CCG tools won't be available. See Troubleshooting below.

For detailed installation instructions, troubleshooting, and platform-specific guides, see docs/INSTALL.md.

Usage

Basic Usage

macOS / Linux:

# Index a single repository
narsil-mcp --repos /path/to/your/project

# Index multiple repositories
narsil-mcp --repos ~/projects/project1 --repos ~/projects/project2

# Enable verbose logging
narsil-mcp --repos /path/to/project --verbose

# Force re-index on startup
narsil-mcp --repos /path/to/project --reindex

Windows (PowerShell / CMD):

# Index a single repository
narsil-mcp --repos C:\Users\YourName\Projects\my-project

# Index multiple repositories
narsil-mcp --repos C:\Projects\project1 --repos C:\Projects\project2

# Enable verbose logging
narsil-mcp --repos C:\Projects\my-project --verbose

# Force re-index on startup
narsil-mcp --repos C:\Projects\my-project --reindex

Full Feature Set

narsil-mcp \
  --repos ~/projects/my-app \
  --git \           # Enable git blame, history, contributors
  --call-graph \    # Enable function call analysis
  --persist \       # Save index to disk for fast startup
  --watch \         # Auto-reindex on file changes
  --lsp \           # Enable LSP for hover, go-to-definition
  --streaming \     # Stream large result sets
  --remote \        # Enable GitHub remote repo support
  --neural \        # Enable neural semantic embeddings
  --neural-backend api \  # Backend: "api" (Voyage/OpenAI) or "onnx"
  --neural-model voyage-code-2 \  # Model to use
  --neural-dimension 3072 \  # Override embedding dimensions (auto-detected per model)
  --graph           # Enable SPARQL/RDF knowledge graph and CCG tools (requires --features graph build)

Note about --graph: This flag enables SPARQL queries and Code Context Graph (CCG) tools, but only if the binary was built with --features graph. The default binary does not include this feature. If you need SPARQL/CCG capabilities, build from source with:
cargo build --release --features graph
If you pass --graph to a binary without the feature, you'll see a warning at startup and the server will continue without SPARQL/CCG tools.

Note: Neural embeddings require an API key (or custom endpoint). The easiest way to set this up is with the interactive wizard:

# Run the neural API key setup wizard
narsil-mcp config init --neural

The wizard will:

Detect your editor (Claude Desktop, Claude Code, Zed, VS Code, JetBrains)
Prompt for your API provider (Voyage AI, OpenAI, or custom)
Validate your API key
Automatically add it to your editor's MCP config

Alternatively, you can manually set one of these environment variables:

EMBEDDING_API_KEY - Generic API key for any provider
VOYAGE_API_KEY - Voyage AI specific API key
OPENAI_API_KEY - OpenAI specific API key
EMBEDDING_SERVER_ENDPOINT - Custom embedding API endpoint URL (optional, allows using self-hosted models)

Configuration

v1.1.0+ introduces optional configuration for fine-grained control over tools and performance. All existing usage continues to work - configuration is completely optional!

Quick Start

# Generate default config interactively
narsil-mcp config init

# List available tools
narsil-mcp tools list

# Apply a preset via CLI
narsil-mcp --repos ~/project --preset minimal

Automatic Editor Detection

narsil-mcp detects your editor and applies an optimal preset automatically:

Editor	Preset	Tools	Context Tokens	Why
Zed	Minimal	26	~4,686	Fast startup, minimal context
VS Code	Balanced	51	~8,948	Good feature balance
Claude Desktop	Full	75+	~12,001	Maximum capabilities

Token Savings:

Minimal preset: 61% fewer tokens vs Full
Balanced preset: 25% fewer tokens vs Full

Presets

Choose a preset based on your use case:

# Minimal - Fast, lightweight (Zed, Cursor)
narsil-mcp --repos ~/project --preset minimal

# Balanced - Good defaults (VS Code, IntelliJ)
narsil-mcp --repos ~/project --preset balanced --git --call-graph

# Full - All features (Claude Desktop, comprehensive analysis)
narsil-mcp --repos ~/project --preset full --git --call-graph

# Security-focused - Security and supply chain tools
narsil-mcp --repos ~/project --preset security-focused

Configuration Files

User config (~/.config/narsil-mcp/config.yaml):

version: "1.0"
preset: "balanced"

tools:
  # Disable slow tools
  overrides:
    neural_search:
      enabled: false
      reason: "Too slow for interactive use"

performance:
  max_tool_count: 50  # Limit total tools

Project config (.narsil.yaml in repo root):

version: "1.0"
preset: "security-focused"  # Override user preset

tools:
  categories:
    Security:
      enabled: true
    SupplyChain:
      enabled: true

Priority: CLI flags > Environment vars > Project config > User config > Defaults

Environment Variables

# Apply preset
export NARSIL_PRESET=minimal

# Enable specific categories
export NARSIL_ENABLED_CATEGORIES=Repository,Symbols,Search

# Disable specific tools
export NARSIL_DISABLED_TOOLS=neural_search,generate_sbom

CLI Commands

# View effective config
narsil-mcp config show

# Validate config file
narsil-mcp config validate ~/.config/narsil-mcp/config.yaml

# List tools by category
narsil-mcp tools list --category Search

# Search for tools
narsil-mcp tools search "git"

# Export config
narsil-mcp config export > my-config.yaml

Learn More:

Configuration Guide - Full configuration reference
Installation Guide - Platform-specific installation

Visualization Frontend

Explore call graphs, imports, symbol references, and control flow interactively in your browser.

# Build with embedded frontend
cargo build --release --features frontend

# Run with HTTP server
narsil-mcp --repos ~/project --http --call-graph
# Open http://localhost:3000

Five graph views:

View	Description
Call Graph	Function call relationships with depth control and direction filtering
Import Graph	File-level import dependencies across the codebase
Symbol Graph	All references to a symbol, with file clustering
Hybrid	Combined call + import graph with split budget
Control Flow	Real CFG with basic blocks, branches, and loop back-edges

Features:

Interactive Cytoscape.js graphs with drag, zoom, and double-click drill-down
Complexity metrics overlay with color coding (green/yellow/orange/red)
Security vulnerability overlay highlighting taint sources and sinks
Six layout algorithms (dagre, force-directed, breadthfirst, concentric, circle, grid)
File tree sidebar with syntax-highlighted code viewer
URL-driven state (shareable links, browser back/forward)
Dark mode support
Node detail panel with code excerpts and navigation to source

Full documentation: See docs/frontend.md for setup, API endpoints, and development mode.

Neural Semantic Search

Find similar code using neural embeddings - even when variable names and structure differ.

# Quick setup with wizard
narsil-mcp config init --neural

# Or manually with Voyage AI
export VOYAGE_API_KEY="your-key"
narsil-mcp --repos ~/project --neural --neural-model voyage-code-2

Supports Voyage AI, OpenAI, custom endpoints, and local ONNX models.

Full documentation: See docs/neural-search.md for setup, backends, and use cases.

Type Inference

Built-in type inference for Python, JavaScript, and TypeScript - no mypy or tsc required.

Tool	Description
`infer_types`	Get inferred types for all variables in a function
`check_type_errors`	Find potential type mismatches
`get_typed_taint_flow`	Enhanced security analysis with type info

def process(data):
    result = data.split(",")  # result: list[str]
    count = len(result)       # count: int
    return count * 2          # returns: int

Forgemax Integration (Experimental)

For large-scale agentic workflows, narsil-mcp can be used through Forgemax — a Code Mode MCP gateway that collapses all 90 tools into just 2 (search + execute), reducing tool schema overhead from ~12,000 tokens to ~1,000.

# Install Forgemax
cargo install forgemax

# Run narsil-mcp through Forgemax (uses forge.toml in repo root)
forgemax

The included forge.toml configures narsil-mcp with sensible defaults:

[servers.narsil]
command = "narsil-mcp"
args = ["--repos", ".", "--git", "--call-graph", "--persist", "--watch"]
transport = "stdio"

[sandbox]
timeout_secs = 10
max_heap_mb = 64
max_concurrent = 8

The LLM writes JavaScript that calls through typed proxy objects inside a sandboxed V8 isolate — credentials, file paths, and internal state never leave the host. This approach is particularly useful when working with multiple MCP servers simultaneously, as it keeps the total tool context small and predictable.

MCP Configuration

Add narsil-mcp to your AI assistant by creating a configuration file. Here are the recommended setups:

Claude Code (.mcp.json in project root - Recommended):

Create .mcp.json in your project directory for per-project configuration:

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

Then start Claude Code in your project:

cd /path/to/project
claude

Using . for --repos automatically indexes the current directory. Claude now has access to 76 code intelligence tools.

Tip: Add --persist --index-path .claude/cache for faster startup on subsequent runs.

For global configuration, edit ~/.claude/settings.json instead. See Claude Code Integration for advanced setups.

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

VS Code + GitHub Copilot (.vscode/mcp.json):

{
  "servers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git", "--call-graph"]
    }
  }
}

Note for Copilot Enterprise: MCP support requires VS Code 1.102+ and must be enabled by your organization administrator.

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", "/path/to/your/projects", "--git"]
    }
  }
}

Zed (settings.json → Context Servers):

{
  "context_servers": {
    "narsil-mcp": {
      "command": "narsil-mcp",
      "args": ["--repos", ".", "--git"]
    }
  }
}

Note for Zed: narsil-mcp starts immediately and indexes in the background, preventing initialization timeouts.

Claude Code Plugin

For Claude Code users, we provide a plugin with slash commands and a skill for effective tool usage.

Install via Marketplace (Recommended):

# Add the narsil-mcp marketplace
/plugin marketplace add postrv/narsil-mcp

# Install the plugin
/plugin install narsil@narsil-mcp

Or install directly from GitHub:

/plugin install github:postrv/narsil-mcp/narsil-plugin

What's included:

Component	Description
`/narsil:security-scan`	Run comprehensive security audits
`/narsil:explore`	Explore unfamiliar codebases
`/narsil:analyze-function`	Deep dive on specific functions
`/narsil:find-feature`	Find where features are implemented
`/narsil:supply-chain`	Analyze supply chain security
Skill	Guides Claude on using 90 tools effectively
MCP Config	Auto-starts narsil-mcp with sensible defaults

See narsil-plugin/README.md for full documentation.

Ralph Automation Integration

Ralph is a Claude Code automation suite for autonomous code development. When narsil-mcp is available, Ralph gains enhanced code intelligence capabilities:

Feature	Without narsil-mcp	With narsil-mcp
Security scanning	Basic (clippy)	OWASP/CWE vulnerability detection
Code understanding	File-based	Call graphs, symbol references
Architecture analysis	Manual	CCG L0/L1/L2 automatic layers
Dependency analysis	cargo tree	Import graphs, circular detection

Setup:

# Install narsil-mcp (Ralph auto-detects it)
cargo install narsil-mcp

# Ralph's quality gates use these tools:
narsil-mcp scan_security --repo <name>
narsil-mcp check_type_errors --repo <name> --path src
narsil-mcp find_injection_vulnerabilities --repo <name>

Ralph gracefully degrades when narsil-mcp is unavailable - all core automation features work without it.

Documentation: See Ralph README for full integration details.

Playbooks & Tutorials

See docs/playbooks for practical usage guides:

Guide	Description
Getting Started	Quick setup and first tool calls
Understand a Codebase	Explore unfamiliar projects
Fix a Bug	Debug with call graphs and taint analysis
Security Audit	Find vulnerabilities with OWASP/CWE scanning
Code Review	Review changes effectively

Each playbook shows the exact tool chains Claude uses to answer your questions.

WebAssembly (Browser) Usage

narsil-mcp can run entirely in the browser via WebAssembly - perfect for browser-based IDEs, code review tools, or educational platforms.

npm install @narsil-mcp/wasm

import { CodeIntelClient } from '@narsil-mcp/wasm';

const client = new CodeIntelClient();
await client.init();
client.indexFile('src/main.rs', rustSourceCode);
const symbols = client.findSymbols('Handler');

Full documentation: See docs/wasm.md for build instructions, React examples, and API reference.

Available Tools (90)

Repository & File Management

Tool	Description
`list_repos`	List all indexed repositories with metadata
`get_project_structure`	Get directory tree with file icons and sizes
`get_file`	Get file contents with optional line range
`get_excerpt`	Extract code around specific lines with context
`reindex`	Trigger re-indexing of repositories
`discover_repos`	Auto-discover repositories in a directory
`validate_repo`	Check if path is a valid repository
`get_index_status`	Show index stats and enabled features

Symbol Search & Navigation

Tool	Description
`find_symbols`	Find structs, classes, functions by type/pattern
`get_symbol_definition`	Get symbol source with surrounding context
`find_references`	Find all references to a symbol
`get_dependencies`	Analyze imports and dependents
`workspace_symbol_search`	Fuzzy search symbols across workspace
`find_symbol_usages`	Cross-file symbol usage with imports
`get_export_map`	Get exported symbols from a file/module

Code Search

Tool	Description
`search_code`	Keyword search with relevance ranking
`semantic_search`	BM25-ranked semantic search
`hybrid_search`	Combined BM25 + TF-IDF with rank fusion
`search_chunks`	Search over AST-aware code chunks
`find_similar_code`	Find code similar to a snippet (TF-IDF)
`find_similar_to_symbol`	Find code similar to a symbol

AST-Aware Chunking

Tool	Description
`get_chunks`	Get AST-aware chunks for a file
`get_chunk_stats`	Statistics about code chunks
`get_embedding_stats`	Embedding index statistics

Neural Semantic Search (requires `--neural`)

Tool	Description
`neural_search`	Semantic search using neural embeddings (finds similar code even with different names)
`find_semantic_clones`	Find Type-3/4 semantic clones of a function
`get_neural_stats`	Neural embedding index statistics

Call Graph Analysis (requires `--call-graph`)

Tool	Description
`get_call_graph`	Get call graph for repository/function
`get_callers`	Find functions that call a function
`get_callees`	Find functions called by a function
`find_call_path`	Find path between two functions
`get_complexity`	Get cyclomatic/cognitive complexity
`get_function_hotspots`	Find highly connected functions

Control Flow Analysis

Tool	Description
`get_control_flow`	Get CFG showing basic blocks and branches
`find_dead_code`	Find unreachable code blocks

Data Flow Analysis

Tool	Description
`get_data_flow`	Variable definitions and uses
`get_reaching_definitions`	Which assignments reach each point
`find_uninitialized`	Variables used before initialization
`find_dead_stores`	Assignments that are never read

Type Inference (Python/JavaScript/TypeScript)

Tool	Description
`infer_types`	Infer types for variables in a function without external type checkers
`check_type_errors`	Find potential type errors without running mypy/tsc
`get_typed_taint_flow`	Enhanced taint analysis combining data flow with type inference

Import/Dependency Graph

Tool	Description
`get_import_graph`	Build and analyze import graph
`find_circular_imports`	Detect circular dependencies
`get_incremental_status`	Merkle tree and change statistics

Security Analysis - Taint Tracking

Tool	Description
`find_injection_vulnerabilities`	Find SQL injection, XSS, command injection, path traversal
`trace_taint`	Trace tainted data flow from a source
`get_taint_sources`	List taint sources (user input, files, network)
`get_security_summary`	Comprehensive security risk assessment

Security Analysis - Rules Engine

Tool	Description
`scan_security`	Scan with security rules (OWASP, CWE, crypto, secrets)
`check_owasp_top10`	Scan for OWASP Top 10 2021 vulnerabilities
`check_cwe_top25`	Scan for CWE Top 25 weaknesses
`explain_vulnerability`	Get detailed vulnerability explanation
`suggest_fix`	Get remediation suggestions for findings

Supply Chain Security

Tool	Description
`generate_sbom`	Generate SBOM (CycloneDX/SPDX/JSON)
`check_dependencies`	Check for known vulnerabilities (OSV database)
`check_licenses`	Analyze licenses for compliance issues
`find_upgrade_path`	Find safe upgrade paths for vulnerable deps

Git Integration (requires `--git`)

Tool	Description
`get_blame`	Git blame for file
`get_file_history`	Commit history for file
`get_recent_changes`	Recent commits in repository
`get_hotspots`	Files with high churn and complexity
`get_contributors`	Repository/file contributors
`get_commit_diff`	Diff for specific commit
`get_symbol_history`	Commits that changed a symbol
`get_branch_info`	Current branch and status
`get_modified_files`	Working tree changes

LSP Integration (requires `--lsp`)

Tool	Description
`get_hover_info`	Type info and documentation
`get_type_info`	Precise type information
`go_to_definition`	Find definition location

Remote Repository Support (requires `--remote`)

Tool	Description
`add_remote_repo`	Clone and index GitHub repository
`list_remote_files`	List files via GitHub API
`get_remote_file`	Fetch file via GitHub API

Metrics

Tool	Description
`get_metrics`	Performance stats and timing

SPARQL / Knowledge Graph (requires `--graph`)

Tool	Description
`sparql_query`	Execute SPARQL query against RDF knowledge graph
`list_sparql_templates`	List available SPARQL query templates
`run_sparql_template`	Execute predefined SPARQL template with parameters

Code Context Graph (CCG) (requires `--graph`)

CCG provides standardized, AI-consumable representations of codebases in tiered layers.

Tool	Description
`get_ccg_manifest`	Layer 0 manifest (~1-2KB JSON-LD) - repo identity, counts
`export_ccg_manifest`	Export Layer 0 manifest to file
`export_ccg_architecture`	Layer 1 architecture (~10-50KB JSON-LD) - modules, API
`export_ccg_index`	Layer 2 symbol index (~100-500KB N-Quads gzipped)
`export_ccg_full`	Layer 3 full detail (~1-20MB N-Quads gzipped)
`export_ccg`	Export all CCG layers as a bundle
`query_ccg`	Query CCG using SPARQL
`get_ccg_acl`	Generate WebACL access control for CCG layers
`get_ccg_access_info`	Get CCG access tier information
`import_ccg`	Import CCG layer from URL or file
`import_ccg_from_registry`	Import CCG from codecontextgraph.com registry

Security Rules

narsil-mcp includes built-in security rules in rules/:

Core Rulesets:

owasp-top10.yaml - OWASP Top 10 2021 vulnerability patterns
cwe-top25.yaml - CWE Top 25 Most Dangerous Weaknesses
crypto.yaml - Cryptographic issues (weak algorithms, hardcoded keys)
secrets.yaml - Secret detection (API keys, passwords, tokens)

Language-Specific Rules:

rust.yaml - Rust security patterns (unsafe transmute, FFI boundaries, command injection, TOCTOU)
elixir.yaml - Elixir/BEAM patterns (atom exhaustion, binary_to_term, Code.eval, Ecto SQL injection)
go.yaml - Go security patterns (SQL injection, TLS, command injection)
java.yaml - Java vulnerabilities (XXE, deserialization, LDAP injection)
csharp.yaml - C# security issues (deserialization, XSS, path traversal)
kotlin.yaml - Kotlin/Android patterns (WebView, intents, secrets)
bash.yaml - Shell script vulnerabilities (command injection, eval)

Infrastructure & Configuration:

iac.yaml - Infrastructure as Code (Terraform, CloudFormation, Kubernetes)
config.yaml - Configuration file security (hardcoded credentials, insecure settings)

Custom rules can be loaded with scan_security --ruleset /path/to/rules.yaml.

Architecture

+-----------------------------------------------------------------+
|                         MCP Server                               |
|  +-----------------------------------------------------------+  |
|  |                   JSON-RPC over stdio                      |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                   Code Intel Engine                        |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  |  |  Symbol    | |   File     | |    Search Engine       |  |  |
|  |  |  Index     | |   Cache    | |  (Tantivy + TF-IDF)    |  |  |
|  |  | (DashMap)  | | (DashMap)  | +------------------------+  |  |
|  |  +------------+ +------------+                              |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  |  | Call Graph | |  Taint     | |   Security Rules       |  |  |
|  |  |  Analysis  | |  Tracker   | |   Engine               |  |  |
|  |  +------------+ +------------+ +------------------------+  |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                Tree-sitter Parser                          |  |
|  |  +------+ +------+ +------+ +------+ +------+             |  |
|  |  | Rust | |Python| |  JS  | |  TS  | | Go   | ...         |  |
|  |  +------+ +------+ +------+ +------+ +------+             |  |
|  +-----------------------------------------------------------+  |
|                              |                                   |
|  +---------------------------v-------------------------------+  |
|  |                Repository Walker                           |  |
|  |           (ignore crate - respects .gitignore)             |  |
|  +-----------------------------------------------------------+  |
+-----------------------------------------------------------------+

Performance

Benchmarked on Apple M1 (criterion.rs):

Parsing Throughput

Language	Input Size	Time	Throughput
Rust (large file)	278 KB	131 µs	1.98 GiB/s
Rust (medium file)	27 KB	13.5 µs	1.89 GiB/s
Python	~4 KB	16.7 µs	-
TypeScript	~5 KB	13.9 µs	-
Mixed (5 files)	~15 KB	57 µs	-

Search Latency

Operation	Corpus Size	Time
Symbol exact match	1,000 symbols	483 ns
Symbol prefix match	1,000 symbols	2.7 µs
Symbol fuzzy match	1,000 symbols	16.5 µs
BM25 full-text	1,000 docs	80 µs
TF-IDF similarity	1,000 docs	130 µs
Hybrid (BM25+TF-IDF)	1,000 docs	151 µs

End-to-End Indexing

Repository	Files	Symbols	Time	Memory
narsil-mcp (this repo)	53	1,733	220 ms	~50 MB
rust-analyzer	2,847	~50K	2.1s	89 MB
linux kernel	78,000+	~500K	45s	2.1 GB

Key metrics:

Tree-sitter parsing: ~2 GiB/s sustained throughput
Symbol lookup: <1µs for exact match
Full-text search: <1ms for most queries
Hybrid search runs BM25 + TF-IDF in parallel via rayon

Development

# Run tests (1763+ tests)
cargo test

# Run benchmarks (criterion.rs)
cargo bench

# Run with debug logging
RUST_LOG=debug cargo run -- --repos ./test-fixtures

# Format code
cargo fmt

# Lint
cargo clippy

# Test with MCP Inspector
npx @modelcontextprotocol/inspector ./target/release/narsil-mcp --repos ./path/to/repo

Troubleshooting

Tree-sitter Build Errors

If you see errors about missing C compilers or tree-sitter during build:

# macOS
xcode-select --install

# Ubuntu/Debian
sudo apt install build-essential

# For WASM builds
brew install emscripten  # macOS

Neural Search API Errors

# Check your API key is set
echo $VOYAGE_API_KEY  # or $OPENAI_API_KEY

# Common issue: wrong key format
export VOYAGE_API_KEY="pa-..."  # Voyage keys start with "pa-"
export OPENAI_API_KEY="sk-..."  # OpenAI keys start with "sk-"

Index Not Finding Files

# Check .gitignore isn't excluding files
narsil-mcp --repos /path --verbose  # Shows skipped files

# Force reindex
narsil-mcp --repos /path --reindex

Memory Issues with Large Repos

# For very large repos (>50K files), increase stack size
RUST_MIN_STACK=8388608 narsil-mcp --repos /path/to/huge-repo

# Or index specific subdirectories
narsil-mcp --repos /path/to/repo/src --repos /path/to/repo/lib

Graph Feature Not Working

If you pass --graph and see a warning like:

WARN: --graph flag was passed but the binary was built without the 'graph' feature.
SPARQL and CCG tools will not be available.

This means you're using a binary that wasn't compiled with the graph feature. To fix:

# Build from source with the graph feature
cargo build --release --features graph

# Or with multiple features
cargo build --release --features graph,frontend

# Then run with --graph
./target/release/narsil-mcp --repos ~/project --graph

Why is this a separate feature? The graph feature adds the Oxigraph RDF database (~5MB additional binary size) which isn't needed for most use cases. It's kept optional to keep the default binary smaller.

How to check if graph is enabled: Look at the startup logs:

graph=true means the feature is compiled in AND enabled
graph=false means either the feature isn't compiled, OR --graph wasn't passed

Roadmap

Completed

What's New

v1.6.x (Current)

Crash-proof chunking - Fixed unsafe byte-level string slicing in chunk_file() and extract_signature() that caused hybrid_search, search_chunks, and get_chunk_stats to crash when processing files with multi-byte UTF-8 characters (emoji, CJK, accented chars). All byte slicing now uses safe content.get() with fallback.
NaN-safe sort operations - Fixed 5 locations across search, embeddings, git, index, and extract modules where partial_cmp().unwrap() would panic on NaN float values. All sorts now use unwrap_or(Ordering::Equal).
Defense-in-depth chunking - Added catch_unwind wrappers around all repo-wide chunk_file() loops so a panic in one file skips it instead of crashing the entire MCP server.
Visualization frontend overhaul - Full SPA with HashRouter routing, file tree sidebar, syntax-highlighted code viewer, dashboard, and per-repo overview pages
Graph view performance - Import graph now uses cached index data instead of filesystem walks; symbol graph iterates file cache directly instead of markdown round-trips; all views respect max_nodes for early termination
Real control flow graphs - Flow view now uses the real CFG builder (cfg::analyze_function) with proper basic blocks, branch conditions, and loop back-edges instead of the single-block stub
Hybrid graph budget splitting - Hybrid view allocates 60/40 node budget between call and import graphs for balanced results
Fix #14: configurable embedding dimensions - Added --neural-dimension CLI arg and default_dimension_for_model() lookup so models like text-embedding-3-large use correct dimensions (3072) instead of hardcoded 1536
Fix #13: Nix frontend build - Added frontendDist derivation in flake.nix using buildNpmPackage so nix profile install github:postrv/narsil-mcp#with-frontend works
Rust security rules - 18 new rules (RUST-004 to RUST-021) covering command injection, transmute, FFI boundaries, TOCTOU, ReDoS, static mut, SSRF, and more
Elixir security rules - 18 new rules (EX-001 to EX-018) covering atom exhaustion, binary_to_term deserialization, Code.eval injection, Ecto SQL injection, Phoenix XSS, Erlang distribution security
Migrated from serde_yaml to serde-saphyr - Deprecated serde_yaml replaced with actively maintained, panic-free YAML library
Custom favicon - Frontend now uses narsil-mcp branding icon instead of default Vite logo
Dependency security - Updated time to 0.3.47 (RUSTSEC-2026-0009), bytes to 1.11.1 (RUSTSEC-2026-0007)
Test count increased from 1,611 to 1,763 (+152 tests)

v1.5.x

Deterministic call graph resolution - Scope-hint propagation disambiguates callee resolution (e.g., App::run() correctly resolves to src/app/mod.rs::run)
8 graph analysis fixes - Qualified node keys, hotspot filtering, CFG expression handling, import path parsing
Nix flake improvements - DRY mkPkg helper, removed unnecessary macOS frameworks, --lib test strategy for sandbox builds

v1.4.x

SPARQL / RDF Knowledge Graph - Query code intelligence data with SPARQL via Oxigraph
Code Context Graph (CCG) - 12 tools for standardized, AI-consumable codebase representations with tiered layers (L0-L3)
Type-aware security analysis - Enhanced taint tracking with type inference and trait implementations
Multi-language CFG/DFG - Control flow and data flow analysis extended to Go, Java, C#, Kotlin
Infrastructure as Code scanning - New iac.yaml rules for Terraform, CloudFormation, Kubernetes
Language-specific security rules - New rules for Go, Java, C#, Kotlin, Bash
6 new languages - Erlang, Elm, Fortran, PowerShell, Nix, Groovy
90 tools total - Up from 79 with new SPARQL, CCG, and analysis capabilities

v1.2.x

exclude_tests parameter - 22 tools support filtering out test files
npm package - Install via npm install -g narsil-mcp

v1.1.x

Multi-platform distribution - Install via Homebrew, Scoop, npm, Cargo, or direct download
Configurable tool presets - Minimal, balanced, full, and security-focused presets
Automatic editor detection - Optimal defaults for Zed, VS Code, Claude Desktop
Interactive setup wizard - narsil-mcp config init for easy configuration
32 language support - Added Dart, Julia, R, Perl, Zig, and more
Improved performance - Faster startup with background indexing

v1.0.x

Neural semantic search - Find similar code using Voyage AI or OpenAI embeddings
Type inference - Infer types in Python/JavaScript/TypeScript without external tools
Multi-language taint analysis - Security scanning for PHP, Java, C#, Ruby, Kotlin
WASM build - Run in browser for code playgrounds and educational tools
147 bundled security rules - OWASP, CWE, crypto, secrets, Rust, Elixir detection
IDE configs included - Claude Desktop, Cursor, VS Code, Zed templates

License

Licensed under either of:

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Credits

Built with:

tree-sitter - Incremental parsing
tantivy - Full-text search
tokio - Async runtime
rayon - Data parallelism
serde - Serialization

Narsil MCP

Installation

Reviews

Documentation

narsil-mcp

Why narsil-mcp?

Key Features

Why Choose narsil-mcp?

Supported Languages

Installation

Via Package Managers (Recommended)

One-Click Install Script

From Source

Feature Builds

Usage

Basic Usage

Full Feature Set

Configuration

Quick Start

Automatic Editor Detection

Presets

Configuration Files

Environment Variables

CLI Commands

Visualization Frontend

Neural Semantic Search

Type Inference

Forgemax Integration (Experimental)

MCP Configuration

Claude Code Plugin

Ralph Automation Integration

Playbooks & Tutorials

WebAssembly (Browser) Usage

Available Tools (90)

Repository & File Management

Symbol Search & Navigation

Code Search

AST-Aware Chunking

Neural Semantic Search (requires --neural)

Call Graph Analysis (requires --call-graph)

Control Flow Analysis

Data Flow Analysis

Type Inference (Python/JavaScript/TypeScript)

Import/Dependency Graph

Security Analysis - Taint Tracking

Security Analysis - Rules Engine

Supply Chain Security

Git Integration (requires --git)

LSP Integration (requires --lsp)

Remote Repository Support (requires --remote)

Metrics

SPARQL / Knowledge Graph (requires --graph)

Code Context Graph (CCG) (requires --graph)

Security Rules

Architecture

Performance

Parsing Throughput

Search Latency

End-to-End Indexing

Development

Troubleshooting

Tree-sitter Build Errors

Neural Search API Errors

Index Not Finding Files

Memory Issues with Large Repos

Graph Feature Not Working

Roadmap

Completed

What's New

v1.6.x (Current)

v1.5.x

v1.4.x

v1.2.x

v1.1.x

v1.0.x

License

Credits

Security Checklist

Neural Semantic Search (requires `--neural`)

Call Graph Analysis (requires `--call-graph`)

Git Integration (requires `--git`)

LSP Integration (requires `--lsp`)

Remote Repository Support (requires `--remote`)

SPARQL / Knowledge Graph (requires `--graph`)

Code Context Graph (CCG) (requires `--graph`)