Docs.rs MCP Server

A Model Context Protocol (MCP) server for fetching Rust crate documentation from docs.rs

Features • Getting Started • Tools • Contributing • Acknowledgments • License

Features

• Find New Crates - Search crates by exact name, partial match, or fuzzy query to discover relevant libraries
• Inspect Crate Symbols - Inspect structs, traits, functions, and any other symbol inside a crate
• Review Crate Summaries - Get a crate overview with its structure and public API surface
• Read Full Documentation - Read crate-level documentation

Getting Started

Using Pre-built Executables

Download the latest release for your platform from the Releases page:

Linux

• x64/AMD64 (GLIBC): mcp-docsrs-linux-x64 - For Ubuntu, Debian, Fedora, etc.
• ARM64 (GLIBC): mcp-docsrs-linux-arm64 - For ARM64 systems, AWS Graviton
• x64/AMD64 (MUSL): mcp-docsrs-linux-x64-musl - For Alpine Linux, Docker containers (requires libstdc++)
• ARM64 (MUSL): mcp-docsrs-linux-arm64-musl - For Alpine on ARM64, minimal containers (requires libstdc++)

macOS

• Intel: mcp-docsrs-darwin-x64 - For Intel-based Macs
• Apple Silicon: mcp-docsrs-darwin-arm64 - For M-series Macs

Windows

• x64: mcp-docsrs-windows-x64.exe - For 64-bit Windows

Using Docker

Pull and run the latest multi-arch image (supports both x64 and ARM64):

# Pull the latest image
docker pull ghcr.io/vexxvakan/mcp-docsrs:latest

# Run the server
docker run --rm -i ghcr.io/vexxvakan/mcp-docsrs:latest

# Run with custom configuration
docker run --rm -i ghcr.io/vexxvakan/mcp-docsrs:latest \
  --cache-ttl 7200000 --max-cache-size 200

Available tags:

• latest - Latest stable release (multi-arch)
• v1.0.0 - Specific version (multi-arch)

MCP Setup

Client	Command
Codex	codex mcp add docsrs -- path/to/mcp-docsrs
Claude Code	claude mcp add --transport stdio docsrs -- path/to/mcp-docsrs
Gemini CLI	gemini mcp add -s user docsrs path/to/mcp-docsrs
OpenCode	Run opencode mcp add, choose a local MCP server, then point it at path/to/mcp-docsrs.
VS Code	Open Command Palette (Cmd/Ctrl+Shift+P) → MCP: Add Server → choose Workspace or User → Command (stdio) → enter path/to/mcp-docsrs.
Cursor	Open Settings (Cmd/Ctrl+Shift+J) → Tools & Integrations → New MCP Server → choose a local/stdio server → enter path/to/mcp-docsrs.

After adding the server, restart the client if it does not discover the tools immediately.

Configuration

Configure the server using environment variables or command-line arguments:

Variable	CLI Flag	Default	Description
CACHE_TTL	--cache-ttl	3600000	Cache time-to-live in milliseconds
MAX_CACHE_SIZE	--max-cache-size	100	Maximum number of cached entries
REQUEST_TIMEOUT	--request-timeout	30000	HTTP request timeout in milliseconds
DB_PATH	--db-path	:memory:	Path to SQLite database file

Tools

The server exposes four MCP tools:

Crate

crate_lookup

Retrieves a crate overview with its structure and public API surface from docs.rs.

Parameter	Type	Required	Description
crateName	string	Yes	Name of the Rust crate to inspect
version	string	No	Specific version or semver range, for example "1.0.0" or "~4"
target	string	No	Target platform, for example "i686-pc-windows-msvc"
formatVersion	number	No	Rustdoc JSON format version

{
  "tool": "crate_lookup",
  "arguments": {
    "crateName": "tokio",
    "version": "1.48.0"
  }
}

crate_docs

Retrieves the crate-level documentation page from docs.rs.

Parameter	Type	Required	Description
crateName	string	Yes	Name of the Rust crate to inspect
version	string	No	Specific version or semver range, for example "1.0.0" or "~4"
target	string	No	Target platform, for example "i686-pc-windows-msvc"
formatVersion	number	No	Rustdoc JSON format version

{
  "tool": "crate_docs",
  "arguments": {
    "crateName": "serde"
  }
}

crate_find

Searches crates.io for matching crates and returns ranked results using fuzzy and partial name matching.

Parameter	Type	Required	Description
query	string	Yes	Search query for crate names
limit	number	No	Maximum number of results to return. Defaults to 10

{
  "tool": "crate_find",
  "arguments": {
    "query": "rustdoc json",
    "limit": 5
  }
}

Symbol

symbol_lookup

Retrieves structured symbol metadata for one symbol inside a crate.

Parameter	Type	Required	Description
crateName	string	Yes	Name of the Rust crate
symbolType	string	Yes	Rustdoc symbol type, for example "struct", "function", or "trait"
symbolname	string	Yes	Symbol name or path, for example "runtime::Runtime" or "spawn"
version	string	No	Specific version or semver range
target	string	No	Target platform

{
  "tool": "symbol_lookup",
  "arguments": {
    "crateName": "tokio",
    "symbolType": "struct",
    "symbolname": "runtime::Runtime"
  }
}

symbol_docs

Retrieves the full documentation body for one symbol inside a crate.

Parameter	Type	Required	Description
crateName	string	Yes	Name of the Rust crate
symbolType	string	Yes	Rustdoc symbol type, for example "struct", "function", or "trait"
symbolname	string	Yes	Symbol name or path, for example "runtime::Runtime" or "spawn"
version	string	No	Specific version or semver range
target	string	No	Target platform

{
  "tool": "symbol_docs",
  "arguments": {
    "crateName": "tokio",
    "symbolType": "struct",
    "symbolname": "runtime::Runtime"
  }
}

Contributing

• See CONTRIBUTING.md.
• See TESTING.md.

Acknowledgments

• docs.rs for providing the Rust documentation API
• Model Context Protocol for the MCP specification
• The Rust community for excellent documentation standards

License

This project is licensed under the Apache License 2.0. See LICENSE for the license text and NOTICE for attribution details.

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