🌿 DevBitsLab.Mcp.SourceGraph

A live code source graph Model Context Protocol server for .NET solutions. It indexes your C# code with Roslyn into a SQLite + FTS5 database, exposes structured graph queries to MCP-aware clients (Claude Code, Cursor, Continue, Claude Desktop, …) over stdio, and keeps the index fresh as files change on disk.

The goal is to let coding agents replace dozens of ad-hoc Grep + Read calls with a single structured tool call:

"Where is OrderService.PublishAsync defined?" "Who calls it transitively, and what would change if I rename it?" "Find every controller action attributed [HttpPost] whose route contains /v2/." "Which tests cover this method, and who authored it last?"

Contents

• Features
• Why not just use Roslyn directly?
• Requirements
• Installation
• Quickstart (60 seconds)
• Wiring it into an MCP client
• MCP tools
• Structured output and resource links
• Resource templates
• Scopes (multi-solution monorepos)
• Command-line interface
• How the index stays live
• Observability
• Resource limits and tunables
• Platform support
• Building from source
• Contributing & security
• License

Features

• Roslyn-backed C# indexing. Symbols, references, call/uses-type/overrides/ implements/instantiates/throws edges, XML doc summaries, accessibility, and modifiers — all queryable in one round-trip.
• Cross-language XAML indexing. Built-in .xaml indexer covering WPF / WinUI 3 / UWP / Avalonia / Uno from a single per-file profile detection step. Cross-language joins (code-behind, handles-event, instantiates-type) point at C# canonical keys via string equality, so find_references on the C# class returns the XAML view that binds it. Five XAML symbol kinds, eight cross-language edge kinds, plus xaml-attached-property annotations for Grid.Row / DockPanel.Dock / etc.
• FTS5 name search. Trigram fragment matching for cases where you only remember "…Greet…Async".
• Optional code-aware semantic search. ONNX embeddings (default model: jinaai/jina-embeddings-v2-base-code) stored in sqlite-vec for natural-language queries like "find the rate-limiting code". Disable with --no-embeddings to skip the model download entirely.
• Attribute search. Find every symbol carrying a given attribute, optionally filtered by serialised argument substring.
• Roslyn diagnostics indexing. Query analyzer warnings/errors captured at index time, by severity, code, or symbol.
• Source-generator awareness. Symbols emitted by incremental generators (regex, MVVM Toolkit, ASP.NET routing, JSON source-gen, …) are tracked and filterable.
• Test discovery & git history. Tests edges from xUnit/NUnit/MSTest tests to the production members they exercise; cached per-symbol git-blame summary (last commit, author, time).
• Multi-solution monorepo scopes. One database per scope, isolation flag for vendored/generated code, fan-out queries with scope = "*".
• Live updates. File watcher + .git/HEAD watcher (worktree-aware), 200 ms debounce, batched re-index. Symbol ids stay stable across edits so existing references remain valid.
• Stable plugin SDK. DevBitsLab.Mcp.SourceGraph.Sdk exposes IMcpToolPlugin for adding bespoke tools that share the same scope router.

Why not just use Roslyn directly?

Roslyn is the right tool when you're writing an analyzer, a refactor, or anything that needs full type-system access live inside the compiler. This server is the right tool when an LLM (or any out-of-process client) needs many cheap structural queries against a stable solution.

Dimension	Roslyn directly (MSBuildWorkspace / SymbolFinder)	This server
Where it runs	In-process API — every client hosts its own workspace	Cross-process MCP server — one host, many clients (Claude Code, Cursor, scripts)
Initial indexing	MSBuildWorkspace load (10–60 s on a real solution), paid in every consumer process	Scope open + full indexing on host start (and after clear or workspace reloads); tool calls await ScopeHost.Ready until the pass completes. Borne once by the host, shared across every connected client.
Steady-state query	Fast in-memory queries against the loaded workspace	Milliseconds — SQLite query against the warm DB; incremental re-indexing handled by the watcher (see Freshness below)
Search shape	Exact-identity lookups (SymbolFinder.FindReferencesAsync)	Same exact lookups plus FTS5 fragment search and ONNX semantic search
Languages	C# / VB only	C# + XAML today, with cross-language joins; plugin SDK for more
Multi-solution	One workspace per solution	Native scope router with isolation flags for vendored / generated code
Freshness	Caller's problem	File watcher + .git/HEAD watcher with 200 ms debounce
Semantic accuracy	100% live	Snapshot-accurate, refreshed on file changes
Type system access	Full (overload resolution, conversions, generic substitution)	Not exposed — graph queries only

In one line: Roslyn is a compiler API; this is a query layer tuned for agents that ask "where does this go?" forty times an hour.

Requirements

• .NET 10 SDK (see global.json).
• A .sln or .slnx solution file for the codebase you want to index.
• An MCP-aware client (Claude Code, Cursor, Continue, Claude Desktop, …).

Installation

Install the published .NET tool globally:

dotnet tool install -g DevBitsLab.Mcp.SourceGraph.Tool

Make sure ~/.dotnet/tools is on your PATH. The installed command is sourcegraph-mcp. You can also pin a version per repository — see Pin a version per repo below.

Quickstart (60 seconds)

From a fresh clone of any .NET solution:

dotnet tool install -g DevBitsLab.Mcp.SourceGraph.Tool
sourcegraph-mcp init        # interactive: detects clients, writes .mcp.json / .vscode/mcp.json / etc.
sourcegraph-mcp demo        # canned probe: ping → graph_stats → search_symbols → find_definition

init writes only project-scoped files by default (.mcp.json, .vscode/mcp.json, .cursor/mcp.json, .continue/mcp/sourcegraph.yaml). User-scope writes (or Claude Desktop) require explicit per-client flags. demo reads the indexed scope and prints the same leaf-stamped markdown your agent will see — instant verification.

Other useful first-run commands:

sourcegraph-mcp init --yes --client copilot,claude-code --print-only   # CI-friendly preview
sourcegraph-mcp doctor                                                  # environment diagnostic
sourcegraph-mcp init --prewarm                                          # also pre-build the index

Wiring it into an MCP client

sourcegraph-mcp init writes the right config for each client below automatically. The snippets here document what each writer produces — useful if you'd rather paste manually, or if you want to understand the schema delta between clients.

Claude Code (project-scoped, committed to the repo)

Drop a .mcp.json at the repository root:

{
  "mcpServers": {
    "sourcegraph": {
      "command": "sourcegraph-mcp",
      "args": ["serve", "--solution", "${workspaceFolder}/MySolution.slnx"]
    }
  }
}

Open the directory in Claude Code and approve the server when prompted. Claude Code expands ${workspaceFolder} automatically; if your client doesn't, the server falls back to the WORKSPACE_FOLDER, CLAUDE_PROJECT_DIR, or MCP_WORKSPACE_FOLDER environment variable. Any other ${VAR} token is expanded against the process environment, so paths like ${HOME}/repos/my.slnx work too.

GitHub Copilot (.vscode/mcp.json)

Copilot's VS Code MCP integration uses a distinct schema from Claude Code's — top-level key is servers (not mcpServers), and each server entry carries an explicit type: "stdio" field:

{
  "servers": {
    "sourcegraph": {
      "type": "stdio",
      "command": "sourcegraph-mcp",
      "args": ["serve", "--solution", "${workspaceFolder}/MySolution.slnx"]
    }
  }
}

Place this at .vscode/mcp.json at the repo root. Pasting the Claude Code snippet here would not work — Copilot silently ignores files that don't match its schema.

Cursor

Cursor uses Claude Code's mcpServers shape. Place at .cursor/mcp.json (project-scope) or ~/.cursor/mcp.json (user-scope):

{
  "mcpServers": {
    "sourcegraph": {
      "command": "sourcegraph-mcp",
      "args": ["serve", "--solution", "${workspaceFolder}/MySolution.slnx"]
    }
  }
}

Continue

Continue uses YAML, one server per file. Place at .continue/mcp/sourcegraph.yaml:

name: sourcegraph
command: sourcegraph-mcp
args:
  - serve
  - --solution
  - ${workspaceFolder}/MySolution.slnx

Claude Desktop

Claude Desktop has no project-scoped config — all MCP servers live in the platform-specific user config:

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json
Linux	~/.config/Claude/claude_desktop_config.json

The shape matches Claude Code:

{
  "mcpServers": {
    "sourcegraph": {
      "command": "sourcegraph-mcp",
      "args": ["serve", "--solution", "/abs/path/to/MySolution.slnx"]
    }
  }
}

Note: ${workspaceFolder} doesn't apply at the user-scope; use absolute paths or set MCP_WORKSPACE_FOLDER in your shell init. init --claude-desktop generates the correct file for you.

Pin a version per repo

dotnet new tool-manifest
dotnet tool install DevBitsLab.Mcp.SourceGraph.Tool
git add .config/dotnet-tools.json

Collaborators run dotnet tool restore once. Pass --install-mode local-tool to init to have the writers emit command: "dotnet" + args: ["sourcegraph-mcp", ...] instead of the global-install shape.

Multi-scope monorepo

Run serve without --solution from the repo root and let it discover .sourcegraph.json:

{
  "mcpServers": {
    "sourcegraph": {
      "command": "sourcegraph-mcp",
      "args": ["serve", "--root", "${workspaceFolder}"]
    }
  }
}

See Scopes below for the configuration format.

MCP tools

Every tool accepts an optional scope parameter (a scope id, a comma-separated list, or "*" for fan-out). Detailed parameter docs are emitted by the server to the client at handshake time.

Discovery & navigation

Tool	Question it answers
find_definition	Where is X defined?
find_references	Who uses or calls X? (file:line list, optionally including source-generated files)
list_callers	Inbound edges into X — default kind=calls; also uses_type, overrides, implements_member, instantiates, throws, all. When an edge carries per-edge metadata (e.g. a future XAML binds-path edge with path, mode, converter fields), the markdown shows an indented payload: { … } sub-line under the row, capped at 5 keys with (N more) if elided.
list_callees	Outbound edges from X (same kind taxonomy; same payload: sub-line behaviour as list_callers).
list_symbols_in_file	What's in this file? (kind, accessibility, modifiers, XML summary)
list_members	Direct members of a class / struct / interface / namespace by FQN, optionally filtered by accessibility
find_implementations	Concrete members satisfying an interface member
neighborhood	Inbound + outbound edges around X for one kind layer at a time (default calls; pass kind=uses_type, overrides, implements_member, instantiates, throws, or all to inspect other layers)
module_summary	Top symbols in a namespace or directory by inbound call count
impact_of_change	Transitive upstream callers of X up to maxDepth
find_data_bindings	Walks binds-path edges with payload-aware filters (path, mode, converter, plus optional target / source canonical keys). Answers "where does this property bind?", "find every TwoWay binding", "which views use this converter?". Soft-empty note: when the active scope hasn't loaded an indexer that emits binds-path.
find_event_handlers	Walks handles-event edges with event / command payload filters and optional handler / element canonical keys. Answers "find all Click handlers", "where is OnSave wired up?". Same soft-empty pattern as find_data_bindings.

Search

Tool	Question it answers
search_symbols	I only have a fragment of the name (FTS5 trigram match on name / FQN / signature)
semantic_search	Natural-language intent search over code embeddings (returns a top-k list with similarity scores)
find_by_attribute	Every symbol carrying an attribute (HttpGet, Obsolete, Authorize, …), optionally filtered by an argValue substring against serialised arguments

Diagnostics, generation, tests, history

Tool	Question it answers
find_diagnostics	Roslyn analyzer/compiler diagnostics captured during indexing — filter by severity, code (e.g. CS0618), or symbol
list_generated_files	Every source-generated file the index tracks, with the count of symbols emitted from each
list_tests_for	Test methods exercising a production symbol (xUnit/NUnit/MSTest), with framework + class
who_authored	Cached git-blame summary for a symbol: last commit sha, author, ISO-8601 time, lines blamed
recent_changes	Symbols whose last authored time falls within the last N days, optionally filtered by author substring

Operations

Tool	Purpose
list_scopes	Enumerate registered scopes (id, name, root, project count, last-indexed time, status, isolation flag)
graph_stats	Counts of files / symbols / references / edges — confirm the index is populated
usage_stats	Per-tool call count, error count, latency, average response size, last-called time for the current process
ping	Health check — returns pong @ <UTC ISO-8601>

Ad-hoc queries (escape hatch)

When no curated tool fits the question — aggregations, joins, "how many public types use X", "which classes implement IDisposable but lack Dispose", "which types have > 50 methods", "which [Obsolete] types have outstanding CS-warnings" — the server exposes a stable view layer over the SQLite tables and a tool to run read-only SQL against it.

Tool	Purpose
describe_schema	Returns the queryable view layer (v_symbols, v_files, v_edges, v_references, v_scopes, v_annotations, v_diagnostics, v_history) with each column's type and description, plus the live symbol_kinds and edge_kinds vocabularies present in the resolved scope set. Call this first when composing query_graph SQL.
query_graph	Runs a single read-only SELECT or WITH statement against the views. Named parameter binding via @name placeholders. Read-only at the SQLite connection level, single-statement enforced at prepare, 5-second statement timeout (configurable), 5000-row cap (configurable). Returns tabular {columns, rows} structured content plus a markdown table. Logged into .sourcegraph/usage.jsonl with the SQL text — the call log is the evidence base for which queries deserve to be promoted into curated tools.

The view layer is versioned (view_schema_version, currently 2); the underlying tables remain implementation details and may evolve without bumping it. The version bumps on any view-set change — addition, removal, column rename, or column-type change — so cache-aware clients always re-introspect after a server upgrade.

The eight views cover: code structure (v_symbols/v_files/v_edges/v_references), scope metadata (v_scopes), attribute / decorator metadata (v_annotations), Roslyn diagnostics (v_diagnostics), and per-symbol git history (v_history). Cross-view JOINs use the composite (scope, id) tuple — see describe_schema's response for the per-column documentation.

Example tool calls

// Where is OrderService.PublishAsync defined?
{ "tool": "find_definition", "args": { "symbol": "OrderService.PublishAsync" } }

// Who would I break if I changed it?
{ "tool": "impact_of_change",
  "args": { "symbol": "OrderService.PublishAsync", "maxDepth": 4 } }

// Every POST controller action whose route contains "/v2/"
{ "tool": "find_by_attribute",
  "args": { "name": "HttpPost", "argValue": "/v2/" } }

// "Find the retry/back-off code"
{ "tool": "semantic_search",
  "args": { "query": "exponential backoff retry policy", "k": 10 } }

// Compiler/analyzer warnings on a specific symbol
{ "tool": "find_diagnostics",
  "args": { "severity": "warning", "symbol": "Legacy.Helpers.OldShim" } }

// What tests cover this before I refactor it?
{ "tool": "list_tests_for", "args": { "symbol": "OrderService.PublishAsync" } }

// Who last touched it, and when?
{ "tool": "who_authored", "args": { "symbol": "OrderService.PublishAsync" } }

// Fan a query out across every non-isolated scope in a monorepo
{ "tool": "find_references",
  "args": { "symbol": "ILogger.LogError", "scope": "*" } }

// Cross-language XAML join — find me the codebehind for this view.
// Returns the C# `csharp:T:SampleWpf.Views.MainWindow` partial-class symbol
// because the XAML indexer wired `<Window x:Class="SampleWpf.Views.MainWindow">`
// to a `code-behind` edge.
{ "tool": "list_callees",
  "args": { "symbol": "Views/MainWindow.xaml", "kind": "code-behind" } }

// Cross-language reverse lookup: every XAML view that points at this codebehind type.
{ "tool": "list_callers",
  "args": { "symbol": "SampleWpf.Views.MainWindow", "kind": "code-behind" } }

// Every element that bound to a viewmodel property (XAML binds-path edge).
// The `payload` sub-line in the response shows the binding's `path`, `mode`,
// `converter`, and friends (see `harden-sdk-pre-xaml`).
{ "tool": "list_callers",
  "args": { "symbol": "MainViewModel.UserName", "kind": "binds-path" } }

// Specialised payload-aware variant: every TwoWay binding to "User.Name".
// Against the SampleWpf fixture this resolves the
// `<TextBox Text="{Binding User.Name, Mode=TwoWay}" />` line in MainWindow.xaml,
// returning one row whose payload carries `path: "User.Name"` and `mode: "two-way"`.
{ "tool": "find_data_bindings",
  "args": { "path": "User.Name", "mode": "two-way" } }

// Every Click handler in the active XAML scope. Against SampleWpf this returns
// the `SaveButton.Click → SampleWpf.Views.MainWindow.OnSave` wiring.
{ "tool": "find_event_handlers",
  "args": { "event": "Click" } }

// Every element with `Grid.Row` set (XAML attached-property annotation).
{ "tool": "find_by_annotation",
  "args": { "name": "Grid.Row", "flavor": "xaml-attached-property" } }

// Ad-hoc SQL: how many public types use Sample.Domain.Calculator?
// Aggregates v_edges through v_symbols.container_id and filters by accessibility=Public.
// No curated tool answers this shape; query_graph composes it from the view layer.
{ "tool": "query_graph",
  "args": {
    "sql": "SELECT COUNT(DISTINCT t.id) AS public_user_count FROM v_edges e JOIN v_symbols m ON m.id = e.src AND m.scope = e.scope JOIN v_symbols t ON t.id = m.container_id AND t.scope = m.scope WHERE e.dst = (SELECT id FROM v_symbols WHERE fqn = @fqn LIMIT 1) AND e.kind = 'uses-type' AND t.is_public = 1 AND t.is_type = 1",
    "parameters": { "@fqn": "Sample.Domain.Calculator" }
  } }

// Schema discovery — list views, columns, and live kind vocabularies.
{ "tool": "describe_schema", "args": {} }

// Composability across the extended views: every public type decorated with
// [Obsolete] that ALSO has at least one outstanding CS-warning. Joins
// v_annotations + v_diagnostics + v_symbols. No curated tool answers the
// intersection; query_graph composes it from the view layer in one round-trip.
{ "tool": "query_graph",
  "args": {
    "sql": "SELECT DISTINCT s.fqn, COUNT(d.id) AS warnings FROM v_annotations a JOIN v_symbols s ON s.id = a.symbol_id AND s.scope = a.scope JOIN v_diagnostics d ON d.symbol_id = s.id AND d.scope = s.scope WHERE a.name = 'Obsolete' AND s.is_public = 1 AND s.is_type = 1 AND d.severity_name = 'warning' GROUP BY s.fqn ORDER BY warnings DESC"
  } }

// Per-symbol git history composability: methods authored > 6 months ago that
// have grown beyond 100 lines (refactor candidates). Joins v_history + v_symbols.
{ "tool": "query_graph",
  "args": {
    "sql": "SELECT s.fqn, h.last_author, h.line_count, datetime(h.last_authored_at / 1000, 'unixepoch') AS last_touched FROM v_history h JOIN v_symbols s ON s.id = h.symbol_id AND s.scope = h.scope WHERE s.kind = 'method' AND h.line_count > 100 AND h.last_authored_at < (strftime('%s', 'now', '-6 months') * 1000) ORDER BY h.line_count DESC"
  } }

Structured output and resource links

Every tool whose result is naturally typed — the symbol-list, edge, diagnostics, history, and singleton tools above — ships two parallel views in each tools/call response:

1. Renderable prose in content — the markdown the human reads in chat. A leading text block carries the substantive answer; per-row resource_link items point at the corresponding graph resources (see the URI table below); a trailing audience: ["assistant"] text block carries diagnostic metadata (resolved scope, query latency, edge-kind defaults, row counts) for the model only.
2. Typed structuredContent — the same data as a JSON object with snake-case field names matching the outputSchema declared on tools/list. Agents that want to chain calls or post-process results can JSON.parse(...) the structured payload directly without re-parsing prose.

The outputSchema for each tool is derived from the C# DTO at registration time, so the wire-level schema stays in lockstep with the implementation. Older MCP clients that don't recognise structuredContent see a complete prose answer; clients that don't recognise resource_link items skip them; clients that respect audience annotations filter the metadata block out of the user view.

graph:// URI scheme

Each resource_link.uri follows one of three shapes:

URI	What it serves
graph://symbol/<id>	Markdown card for one symbol — signature, summary, location, attributes, top neighbours
graph://file/<url-encoded-path>	Symbol outline for a file — every class/method/property declared, with line numbers
graph://namespace/<name>	Namespace summary — top symbols by inbound call count

A client that supports resources/read can dereference any emitted URI for an expanded card; the server resolves it against the active scope. See Resource templates for the underlying MCP templates.

Sample find_definition payload

A find_definition({"symbol": "Calculator"}) call against the Sample fixture returns:

{
  "content": [
    {
      "type": "text",
      "text": "🌿 6 hits for 'Calculator':\n- **Sample.Domain.Calculator** (public class)\n  - /abs/path/Calculator.cs:12:18\n  - …"
    },
    {
      "type": "resource_link",
      "uri": "graph://symbol/12",
      "name": "Sample.Domain.Calculator",
      "title": "Sample.Domain.Calculator",
      "description": "public class — /abs/path/Calculator.cs:12:18",
      "mimeType": "text/markdown"
    },
    // … one resource_link per hit, in the same order as the prose rows …
    {
      "type": "text",
      "text": "_meta: scope=`default`, latency_ms=12, hits=6_",
      "annotations": { "audience": ["assistant"], "priority": 0.2 }
    }
  ],
  "structuredContent": {
    "hits": [
      {
        "fqn": "Sample.Domain.Calculator",
        "kind": "class",
        "file_path": "/abs/path/Calculator.cs",
        "line": 12,
        "column": 18,
        "signature": "public class Calculator",
        "xml_summary": "Multiply, divide, add — the four basics."
      }
      // … one entry per resource_link, same order …
    ]
  }
}

A downstream tool that chains on this result reads result.structuredContent.hits[i] directly — the typed array length always equals the number of resource_link items and the number of prose rows. Plugin tools that opt into the same shape return a CallToolResult from their handler; the SDK marshals the wire shape identically to the built-ins.

Resource templates

Hosts that surface MCP resources can dereference these URIs:

URI template	Returns
graph://symbol/{symbolId}	Markdown card for one symbol (signature, summary, location, attributes, neighbours)
graph://file/{path}	Markdown listing of every symbol declared in a file
graph://namespace/{name}	Markdown summary of a namespace (members, top inbound symbols)

Scopes (multi-solution monorepos)

A .sourcegraph.json at the repo root opts a project into multi-scope mode:

{
  "scopes": [
    { "name": "frontend", "solutions": ["src/frontend.slnx"] },
    { "name": "backend",  "solutions": ["src/backend.slnx"], "exclude": ["**/Generated/**"] }
  ],
  "default_scope": "backend"
}

• Each scope owns its own SQLite database at .sourcegraph/scopes/<id>.db.
• A _meta.db registry tracks per-scope status (ok | partial | degraded | indexing) and last-indexed timestamp.
• isolated: true excludes a scope from scope = "*" fan-out — useful for vendored or generated code that shouldn't pollute references on production symbols.
• Without a .sourcegraph.json and without --solution, a synthesised default scope keeps single-solution users working unchanged.
• The legacy single-database layout (.sourcegraph/graph.db) is migrated to scopes/default.db automatically on first start.
• Live indexing currently resolves a Roslyn workspace per scope only for solutions-based scopes. Scopes declared via projects or paths are accepted by the config loader but are not indexed by the live server yet — prefer solutions for now.
• A running server picks up .sourcegraph.json edits live (no restart). Adds, removes, modifications, and default_scope changes flow through immediately; malformed saves are tolerated and never tear down working scopes. Plugin entries (plugins[]) still require a restart to apply.

Every tool accepts an optional scope parameter — pass an id, a comma-separated list, or "*" to fan out.

Partial indexing (one bad project doesn't take down the scope)

Real-world solutions often contain at least one quirky project (legacy MSBuild quirks, missing source generator NuGet, in-progress migration). Rather than marking the whole scope degraded when a single project's compilation fails, the indexer isolates per-project and per-file failures and surfaces them on list_scopes:

• A project whose Compilation cannot be obtained (probe failure) is recorded in failed_projects with a short reason string. Its documents are excluded from every subsequent indexing pass; the rest of the solution indexes normally.
• A file whose Pass 1 symbol walk throws (rare — a transient Roslyn state, a generator-affected source going wonky) is recorded in failed_files. The file's prior store state is preserved untouched until the next successful walk.

Status semantics:

Status	Meaning
ok	Every project and file indexed cleanly. failed_projects / failed_files are empty.
partial	At least one project produced symbols and at least one project or file failed. Tools serve best-effort results from healthy projects; consult list_scopes for the failure detail.
degraded	Workspace failed to open, OR every project failed. Tools return "scope is degraded: <error>".
indexing	Cold index in progress.

Tool fan-out (scope = "*") targets every non-isolated scope regardless of status. Healthy and partial scopes return query results; degraded scopes contribute a per-scope error block (scope is degraded: <message>) to the merged response so operators see why a scope returned no data without the call failing as a whole. Querying a partial scope by id returns the indexed symbols (best-effort); use list_scopes to see what's missing.

Command-line interface

sourcegraph-mcp <subcommand> [options]

Subcommand	Description
serve	Run the MCP stdio server. With --solution registers an implicit default scope; otherwise reads .sourcegraph.json from --root (or CWD).
index <solution>	Build/refresh the database for a single solution, then exit. Useful in CI.
stats	Print counts of files / symbols / references / edges in the database.
clear	Delete all rows from the database (schema preserved).
init [--yes] [--client <id>] [--no-<client>] [--user-<client>] [--claude-desktop] [--print-only] [--force] [--prewarm] [--install-mode <mode>]	Interactive (default) or flag-driven onboarding flow. Detects environment, picks MCP clients, writes per-client config files (project-scoped by default), and optionally pre-warms the index. First-class clients: claude-code, copilot, cursor, continue, claude-desktop. Use --print-only for a CI-friendly preview that writes nothing.
doctor [--json]	Read-only environment diagnostic. Reports SDK / git / solution / config / per-client status. Exit 0 = all-pass; 2 = at least one warning; 1 = hard failure. --json emits a machine-readable {checks, exit_code} document.
demo [--scope <id>] [--no-color]	Run four canned operations (ping, graph_stats, search_symbols, find_definition) against the active scope and print leaf-stamped markdown — the same shape an MCP client would see. Provides the "ah, it works" confidence moment without an agent loop. Exits 2 if the scope has zero symbols indexed.
init-scopes	Discover .slnx/.sln files at --root (default: CWD) and write a starter .sourcegraph.json. Continues to work standalone; init invokes the same scaffolding internally when multi-solution is detected.
scopes list [--root <path>]	List the scopes declared in .sourcegraph.json.
scopes add <name> --solution <path> [--root <path>] [--isolated]	Add a scope. The file is created on first use.
scopes remove <name> [--root <path>]	Remove a scope.
plugins list [--root <path>]	List plugins declared in .sourcegraph.json with their version, status, registered contracts, and source path.
plugins info <name> [--root <path>]	Show the full record for one plugin: status reason, declared interfaces, registered tool names.
vocabulary list [--root <path>] [--scope <id>] [--strict]	Per-scope diagnostic over the soft-registry kind vocabulary. Lists edge_kinds / symbol_kinds / annotation_flavors with each entry tagged by source (sdk constant vs plugin: <id>@<version> vs unknown) and live emission count, plus a "Drift candidates" section flagging Levenshtein-near pairs (bind-path ~ binds-path) within the same scope. Default exit 0; --strict exits 2 on any drift candidate so CI can wire it as a gate.

Common flags:

Flag	Effect
--solution <path>, -s	Path to a .sln / .slnx.
--db <path>	Override the database path for the one-shot commands (index, stats, clear). Ignored by serve, which always uses the per-scope layout under <root>/.sourcegraph/scopes/<id>.db.
--root <path>	Repository root used for .sourcegraph.json discovery and scope databases. Defaults to the directory holding --solution, then CWD.
--model <id>	Override the embedding model identity (default jinaai/jina-embeddings-v2-base-code). Applies to serve and index.
--no-embeddings	Skip the embedding pipeline entirely (no model download, no vec0 writes). semantic_search returns a disabled message; every other tool works as before.
--no-history	Disable the git-blame history pipeline. Use in environments without git on PATH or in CI where per-symbol history isn't needed.
--no-instructions	Don't publish server-side usage guidance in the MCP initialize response. By default the server tells the connected model to prefer source-graph tools over Grep + Read for symbol-level questions and to call usage_stats at end-of-turn to verify. Equivalent to setting SOURCEGRAPH_NO_INSTRUCTIONS=1.
--no-leaf	Don't prefix the brand mark 🌿 onto any of the three surfaces the server stamps: per-call response prose (the first user-visible text block of every built-in tool's result), the published ServerInstructions string, and the per-tool catalog identity (Tool.Title becomes 🌿 <name> and Tool.Description is prefixed with 🌿 in tools/list). By default the brand mark surfaces in all three places so the agent (and the human reading the chat) can tell at a glance that the answer came from this server. Use this knob if your terminal renders emoji as monospaced fallback boxes or if you simply prefer unbranded output. Equivalent to setting SOURCEGRAPH_NO_LEAF=1. Independent of --no-instructions.

Examples:

sourcegraph-mcp index ./MySln.sln
sourcegraph-mcp serve --solution ./MySln.sln
sourcegraph-mcp serve --root ./repo --no-embeddings
sourcegraph-mcp init-scopes
sourcegraph-mcp scopes add backend --solution ./backend.slnx
sourcegraph-mcp stats --db ./.sourcegraph/scopes/default.db

How the index stays live

• Recursive *.cs file watcher that ignores obj/, bin/, .git/, and .sourcegraph/.
• .git/HEAD watcher — also handles git worktrees by parsing gitdir: from the .git file — so branch switches trigger a re-blame.
• 200 ms debounce window with batched re-indexing.
• Each canonical symbol keeps a stable id across edits, so references from other files remain valid even after rapid local changes.

Recovery from incomplete indexing

The indexer self-heals from incomplete prior passes on the next start; no operator action is needed. Pass 1's "unchanged file" SHA-skip path verifies that each symbol-bearing file has at least one pass-2 artifact in the store (an outgoing reference row, or an outgoing edge from a symbol declared in the file) before skipping pass 2 — files whose refs and edges were cleared but never repopulated (transient compilation gaps, exceptions partway through a walk) are detected and re-walked automatically.

When the integrity check forces a recovery, the indexer emits an info-level log line per affected file: "Re-walking references for {Path}: file SHA matches but no outgoing references in store …". Healthy installs never see this line. Repeated recoveries on the same files would indicate a regression in the upstream indexing flow worth investigating.

Observability

The server emits three signals you can hook into:

1. JSONL audit log — every tool call appends one line to <root>/.sourcegraph/usage.jsonl, capturing timestamp, tool name, args, scope, latency, response size, and error state. Suitable for offline analysis or compliance archival.

2. usage_stats MCP tool — returns in-process counters (call count, error count, average / max latency, average response size, last-called time) for the current process. Use it at end-of-turn to verify the agent reached for the graph instead of falling back to Grep + Read.

3. OpenTelemetry signals — the server emits spans on ActivitySource("DevBitsLab.Mcp.SourceGraph") and metrics on Meter("DevBitsLab.Mcp.SourceGraph"). Counters: sourcegraph.tool.calls, sourcegraph.tool.errors. Histograms: sourcegraph.tool.duration (ms), sourcegraph.tool.response_size (bytes). Tags: mcp.tool, mcp.tool.ok, mcp.tool.scope. Both signals are zero-cost when no listener is attached; pick them up with the OpenTelemetry SDK or dotnet-counters monitor --name sourcegraph-mcp DevBitsLab.Mcp.SourceGraph.

4. MCP notifications/progress — four tools opt in to live progress reporting: semantic_search (three checkpoints around ONNX-model load + vector search + formatting), impact_of_change, module_summary (one starting checkpoint each), and find_definition (cold-start phase progress only — see below). Cold-start visibility: when one of the progress-aware tools is invoked against a scope whose initial indexing isn't finished, the server forwards per-scope IIndexingProgressSource events as notifications/progress for the duration of the wait — three coarse phases (opening workspace → indexing → ready) so the chat panel sees motion instead of a silent spinner. Clients opt in by sending a progressToken field on the originating tools/call request:

   {
     "method": "tools/call",
     "params": {
       "name": "semantic_search",
       "arguments": {"query": "retry on transient errors"},
       "_meta": {"progressToken": "any-string-or-int"}
     }
   }
   

   When no progressToken is set, the server emits zero progress messages — the wire fast-path is unchanged. When set, the server emits one notifications/progress message per checkpoint with a normalised progress value in [0, 1] and a short message (encoding query, searching, formatting results, querying).

Resource limits and tunables

The server is designed to stay inside a single process and a single SQLite database per scope. The current limits are:

Limit	Default	How to change
Roslyn analyzer timeout per document	30 s	Hard-coded in AnalyzerPipeline; override via fork.
File-watcher debounce window	200 ms	Hard-coded in SolutionWatcher.
Default SearchSymbols / find_references / list_members result limit	25 / 50 / 100 rows	Pass limit on the MCP tool call. A soft serialized-size cap (~50K chars) trims further if a larger limit would exceed Claude Code's per-call ceiling; trim is signalled via omitted_size=N in the audience-restricted _meta: block.
impact_of_change max depth	4 hops	Pass maxDepth on the tool call.
semantic_search top-k default	10	Pass k on the tool call.
Embedding model download	~480 MB	Disable with --no-embeddings.
Per-symbol git blame shellout	enabled	Disable with --no-history.
MCP initialize instructions payload	enabled	Disable with --no-instructions or SOURCEGRAPH_NO_INSTRUCTIONS=1.
Green-leaf brand mark on tool responses, ServerInstructions, and per-tool Title/Description in tools/list	enabled	Disable with --no-leaf or SOURCEGRAPH_NO_LEAF=1.
SQLite database size per scope	unbounded	Use clear to wipe; databases live under <root>/.sourcegraph/scopes/<id>.db.
query_graph statement timeout	5 s	--query-timeout-seconds <int> or SOURCEGRAPH_QUERY_TIMEOUT_SECONDS=<int>.
query_graph row cap	5000 rows	--query-row-limit <int> or SOURCEGRAPH_QUERY_ROW_LIMIT=<int>. The tool surfaces truncated: true when the cap is hit.

The curated tools have no built-in timeout — they honour the MCP client's CancellationToken through every async graph operation. The query_graph tool DOES enforce a per-call statement timeout (above) so an accidental Cartesian join doesn't pin the server.

Platform support

Platform	Build / test in CI	Distribution
Linux x64 / arm64	Ubuntu (latest) on every push and PR	dotnet tool install -g
macOS arm64 / x64	macOS (latest) on every push and PR	dotnet tool install -g
Windows x64	Windows (latest) on every push and PR	dotnet tool install -g

The published tool targets net10.0. Earlier .NET runtimes (8, 9) are not currently supported — see GOVERNANCE.md for the LTS-multi-TFM roadmap.

The configuration schema for .sourcegraph.json is published as JSON Schema at schema/sourcegraph.schema.json — most editors will validate your config if you add a top-level "$schema": "./schema/sourcegraph.schema.json".

Building from source

git clone https://github.com/Jak3b0/DevBitsLab.Mcp.SourceGraph.git
cd DevBitsLab.Mcp.SourceGraph
dotnet build
dotnet test

To point a project's .mcp.json at your local checkout instead of the published tool, swap command / args for:

{
  "command": "dotnet",
  "args": [
    "run", "--project",
    "${workspaceFolder}/path/to/DevBitsLab.Mcp.SourceGraph/src/DevBitsLab.Mcp.SourceGraph.Server",
    "--no-build", "--no-launch-profile", "--verbosity", "quiet",
    "--", "serve", "--solution", "${workspaceFolder}/MySolution.slnx"
  ]
}

Re-run dotnet build after each change so the next launch picks it up.

Contributing & security

• Contribution workflow, coding conventions, and the MCP-tool authoring checklist live in CONTRIBUTING.md.
• The architecture overview and module layout live in docs/ARCHITECTURE.md.
• Vulnerability disclosure is documented in SECURITY.md — please do not open public issues for security problems.
• Project governance, decision-making, and the deprecation policy live in GOVERNANCE.md.
• A running history of changes is in CHANGELOG.md.

License

Released under the MIT License.