Rust Docs Mcp

[](https://github.com/snowmead/rust-docs-mcp)

Rustdocs MCP Server

[](https://crates.io/crates/rust-docs-mcp) [](https://opensource.org/licenses/MIT) [](https://discord.gg/ak2yTNN7) [](https://github.com/snowmead/rust-docs-mcp/actions) [](https://deepwiki.com/snowmead/rust-docs-mcp)

Rust is the language of AI

An MCP (Model Context Protocol) server that provides comprehensive access to Rust crate documentation, source code analysis, dependency trees, and module structure visualization. Built for agents to gain quality insights into Rust projects and build with confidence.

Warning

This is an entirely vibe coded project and was created as an experiment to see if LLMs can build a fully functional tool without human oversight.

The Problem: Agents Building in the Dark

The rise of AI agents has revolutionized software development, with new tools and libraries emerging at an unprecedented pace. However, this rapid evolution creates a critical challenge: agents cannot reliably build with tools they weren't trained on.

When an agent tries to use a new Rust crate:

• 🚫 Training data is outdated — The model hasn't seen recent crates or API

changes

• 🚫 Documentation scraping is inefficient — Web scraping GitHub or docs.rs

is slow and unreliable

• 🚫 Examples aren't enough — Copy-pasting README examples provides

surface-level understanding

• 🚫 Internal structure is opaque — Agents can't explore how modules,

traits, and types interconnect

This leads to frustrated developers watching their agents fail repeatedly, guessing at APIs, and producing broken code.

The Solution: Deep Crate Intelligence

This MCP server gives agents the tools they need to truly understand Rust crates:

• 🔍 Explore internal structure — Navigate module hierarchies and type

relationships

• 📖 Access complete documentation — Full rustdoc with signatures, fields,

and methods

• 🔗 Trace dependencies — Understand what a crate depends on and why
• 💾 Work offline — Cache crates locally for instant, reliable access
• 🎯 Query precisely — Search by pattern, kind, or path to find exactly

what's needed

With these capabilities, agents can build confidently with any Rust crate — even ones released yesterday.

Agent Capabilities

• [x] Multi-source caching — crates.io, GitHub repositories, local

filesystem paths

• [x] Workspace support — Individual member analysis and caching for cargo

workspaces

• [x] Documentation search — Pattern matching with kind/path filtering and

preview modes

• [x] Item inspection — Detailed signatures, fields, methods, and

documentation strings

• [x] Source code access — Line-level precision with parameterized

surrounding context

• [x] Dependency analysis — Direct and transitive dependency trees with

metadata

• [x] Module structure — Hierarchical tree generation via cargo-modules

integration

• [x] Offline operation — Full functionality after initial crate caching
• [x] Token management — Response truncation and preview modes for LLM

compatibility

MCP Tools

Cache Management

• cache_crate - Download and cache a crate from various sources. Set

source_type to one of: cratesio, github, or local

• For cratesio: Provide version (e.g., {crate_name: "serde", source_type: "cratesio", version: "1.0.215"})
• For github: Provide github_url and either branch OR tag (e.g., {crate_name: "my-crate", source_type: "github", github_url: "https://github.com/user/repo", tag: "v1.0.0"})
• For local: Provide path, optional version (e.g., {crate_name: "my-crate", source_type: "local", path: "~/projects/my-crate"})
• remove_crate - Remove cached crate versions to free disk space
• list_cached_crates - View all cached crates with versions and sizes
• list_crate_versions - List cached versions for a specific crate
• get_crates_metadata - Batch metadata queries for multiple crates

Documentation Queries

• list_crate_items - Browse all items in a crate with optional filtering
• search_items - Full search with complete documentation (may hit token

limits)

• search_items_preview - Lightweight search returning only IDs, names, and

types

• get_item_details - Detailed information about specific items (signatures,

fields, etc.)

• get_item_docs - Extract just the documentation string for an item
• get_item_source - View source code with configurable context lines

Dependency Analysis

• get_dependencies - Analyze direct and transitive dependencies with filtering

Structure Analysis

• structure - Generate hierarchical module tree using integrated cargo-modules

Search

• search_items_fuzzy - Fuzzy search with typo tolerance and semantic

similarity

Configuration

Cache Directory

By default, crates are cached in ~/.rust-docs-mcp/cache/. You can customize this location using:

# Command line option
rust-docs-mcp --cache-dir /custom/path/to/cache
# or set the environment variable
export RUST_DOCS_MCP_CACHE_DIR=/custom/path/to/cache
rust-docs-mcp

GitHub Authentication

To access private repositories or increase GitHub API rate limits, set the GITHUB_TOKEN environment variable:

export GITHUB_TOKEN=your_github_personal_access_token

Benefits of authentication:

• Access private repositories — Cache and analyze private Rust crates
• Higher rate limits — 5,000 requests/hour (vs 60 unauthenticated)
• Avoid rate limit errors — Essential for caching multiple GitHub-hosted

crates

Each crate version stores

• Complete source code in source/ directory
• Cache metadata and timestamps in metadata.json
• For workspace crates, individual members in members/ directory:
• members/{member-name}/docs.json - Rustdoc JSON documentation
• members/{member-name}/dependencies.json - Cargo dependency metadata
• members/{member-name}/metadata.json - Member-specific cache metadata
• For single crates:
• docs.json - Rustdoc JSON documentation
• dependencies.json - Cargo dependency metadata

Installation

Quick Install

curl -sSL https://raw.githubusercontent.com/snowmead/rust-docs-mcp/main/install.sh | bash

Installation Options

One-liner (Recommended)

curl -sSL https://raw.githubusercontent.com/snowmead/rust-docs-mcp/main/install.sh | bash

Custom install directory

curl -sSL https://raw.githubusercontent.com/snowmead/rust-docs-mcp/main/install.sh | bash -s -- --install-dir /usr/local/bin

Cargo Install

cargo install rust-docs-mcp

Building from Source

Requirements

• Rust nightly toolchain (for Rustdoc JSON generation)

``bash rustup toolchain install nightly ``

Runtime prefers nightly-2025-06-24 because it matches the rustdoc JSON schema used by rustdoc-types, but it will fall back to nightly when that toolchain produces the same JSON format version. You can override the choice with:

``bash export RUST_DOCS_MCP_TOOLCHAIN=nightly ``

• Network access to download crates from crates.io

git clone https://github.com/snowmead/rust-docs-mcp
cd rust-docs-mcp/rust-docs-mcp
cargo build --release
./target/release/rust-docs-mcp install

CLI Commands

rust-docs-mcp                   # Start MCP server
rust-docs-mcp install           # Install to ~/.local/bin
rust-docs-mcp install --force   # Force overwrite existing installation
rust-docs-mcp doctor            # Verify system environment and dependencies
rust-docs-mcp doctor --json     # Output diagnostic results in JSON format
rust-docs-mcp update            # Update to latest version from GitHub
rust-docs-mcp --help            # Show help

Troubleshooting

If you encounter issues during installation or runtime, run the doctor command to diagnose common problems:

rust-docs-mcp doctor

The doctor command checks:

• Rust toolchain availability (stable + nightly)
• Git installation
• Network connectivity to crates.io and GitHub
• Cache directory permissions and disk space
• Rustdoc JSON generation capability
• Optional dependencies (e.g., codesign on macOS)

For programmatic integration, use --json flag to get structured output.

MCP Configuration

Add the server to your MCP configuration:

{
  "rust-docs": {
    "command": "/path/to/rust-docs-mcp/target/release/rust-docs-mcp",
    "transport": "stdio"
  }
}

Star History

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: snowmead
• Source: snowmead/rust-docs-mcp
• License: MIT

Install and usage instructions live in the source repository linked above.