[](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.
## 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- 🚫 **Training data is outdated** — The model hasn't seen recent crates or API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_from_cratesio` - Download and cache a specific crate version from
crates.io for offline use
- `cache_crate_from_github` - Download and cache from GitHub (specify branch or
tag)
- `cache_crate_from_local` - Cache from a local file system path
- `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:
```bash
# 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:
```bash
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
```bash
### Installation Options
#### One-liner (Recommended)
```bash
#### Custom install directory
```bash
#### Cargo Install
```bash
cargo install rust-docs-mcp
```
#### Building from Source
##### Requirements
- Rust nightly toolchain (for Rustdoc JSON generation)
```bash
rustup toolchain install nightly
```
- Network access to download crates from [crates.io](https://crates.io)
```bash
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
```bash
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:
```bash
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:
```json
{
"rust-docs": {
"command": "/path/to/rust-docs-mcp/target/release/rust-docs-mcp",
"transport": "stdio"
}
}
```
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