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MCP server · Developer Tools

Effect MCP

by · github.com/niklaserik/effect-mcp

A mcp server for fetching the Effect-ts documentation

Unclaimed MIT last commit 7 months ago devtools
InstallView source
54Fair

Scored 13 days ago · breakdown

About Effect MCP

Effect MCP is an MCP server published by niklaserik in the Developer Tools category: a mcp server for fetching the Effect-ts documentation.

The repository has 45 stars and 4 forks, with the last commit 7 months ago. Six months or more without a commit doesn't mean the server is broken, but check the open issues before depending on it in production.

Install

From source
git clone https://github.com/niklaserik/effect-mcp

This server has no ConduID identity, so agent calls to it are not receipted. Pin the version you install and review the source before granting it credentials.

Tools (2)

effect-doc-linksReturns resource links for the specified libraries so the client can load only what

Parameters not published.

effect-documentationFetches and concatenates the latest docs for the specified Effect libraries.

Parameters not published.

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Security checks

Static checks derived from the repository 6 days ago. Heuristics on the source, not an audit.

  • ✓README presentThe repository ships documentation.
  • ✓License declaredUsable under a stated license.
  • !Tests presentNo tests found. Behaviour changes may go unnoticed between versions.
  • ✓Dependencies pinnedA lockfile pins dependency versions.
  • ✓No dynamic code executionSource scan found no eval, dynamic Function, or shell execution.
  • !Scoped permissionsDoesn't declare a permission scope. Assume it can do anything its process can.

README

@niklaserik/effect-mcp

A Model Context Protocol (MCP) server dedicated to fetching the most current documentation from the Effect ecosystem.

Purpose

This MCP server provides real-time access to Effect documentation for AI assistants and tools. It enables VS Code extensions and other MCP clients to retrieve accurate and up-to-date Effect package documentation to assist developers with questions about:

  • The core effect package
  • Ecosystem packages (@effect/platform, @effect/ai, etc.)
  • Both stable and unstable Effect packages

The server intelligently detects imported Effect packages in your code and fetches the most relevant documentation to answer your queries.

Features

  • Real-time documentation access for Effect ecosystem
  • Support for both stable and experimental packages
  • Context-aware package detection based on imports
  • Seamless integration with VS Code and other MCP-compatible clients
  • Helps answer API usage questions for Effect developers

What this server exposes

  • Resources (preferred)
    • Dynamic template: effect-docs://{libId}
    • Completions on {libId} and resource listing are supported
    • Static aliases for discovery: effect-docs://effect, effect-docs://@effect-platform, etc.
    • Supported libraries (as of now):
      • effect
      • @effect/platform
      • @effect/sql
      • @effect/vitest
      • @effect/ai
      • @effect/cli
      • @effect/cluster
      • @effect/rpc
      • @effect/typeclass
  • Tools (for compatibility)
    • effect-documentation: fetch docs for selected libraries and return concatenated markdown
    • effect-doc-links: return plain URIs to the resources above so clients can follow them

Caching & Retry

  • In-memory TTL cache (~10 minutes) to avoid refetching unchanged docs.
  • Lightweight retry with small backoff on transient fetch errors.

Installation

pnpm add @niklaserik/effect-mcp

Usage

For usage in VS Code or other MCP clients, refer to the client's documentation for adding custom MCP servers.

Quick test locally:

pnpm install
pnpm build
node dist/index.js # stdio transport

Then connect with an MCP client (e.g., MCP Inspector) over stdio and try:

  • List resources and read effect-docs://effect
  • Call tool effect-doc-links with { "libraries": ["effect", "@effect/platform"] }

Initialization instructions

  • The server publishes short usage instructions via MCP initialize for clients that display them.

Development

# Install dependencies
pnpm install

# Build the project
pnpm build

# Run in development mode with auto-reload
pnpm dev

Notes:

  • Built with @modelcontextprotocol/sdk@^1.17.4 using the modern registerResource/registerTool APIs.
  • Transport: stdio by default; can be adapted to Streamable HTTP if needed.

License

MIT

README fetched from the repository 6 days ago. The original is authoritative.

Questions

About Effect MCP

How do I install Effect MCP?

No package has been published for this server, so install it from source: clone the repository and follow its README.

Is Effect MCP safe to use with an AI agent?

Its trust score is 54 out of 100 (fair). It passes 4 of the 6 static security checks run so far; the failures are listed above. It has no ConduID identity yet, so agent calls to it are not receipted.

Is Effect MCP still maintained?

The last commit was 7 months ago. That's long enough that you should check whether the maintainer is responding to issues before depending on it.