Rust Docs MCP Server

Install

Works in

• Cursor
• Cline
• Roo Code
• SourceCraft
• Koda
• Coddy

Manual install

{
  "mcpServers": {
    "rust-docs-reqwest": {
      "command": "/path/to/your/rustdocs_mcp_server",
      "args": ["reqwest@0.12"],
      "env": {"OPENAI_API_KEY": "YOUR_OPENAI_API_KEY_HERE"}
    }
  }
}

What it does

Rust Docs MCP Server starts for one crate and gives the agent the query_rust_docs tool. The agent asks a question such as "how do I make a simple GET with reqwest", and the server finds the relevant documentation sections and answers from them without relying on model memory. The crate is set with a Cargo spec such as `serde@^1.0` or `reqwest@0.12.0`, and the `-F` flag turns on the crate features needed. On first start the server builds the docs with `cargo doc`, parses the HTML and builds embeddings through OpenAI with the text-embedding-3-small model. gpt-4o-mini writes the answer from the retrieved context. Documentation and embeddings are cached in the XDG data directory separately for each crate, version and feature set, so later starts are fast. The crate://<name> resource reports which crate a server is set up for.

Who it is for. For Rust developers working with Cursor, Cline or Roo Code who want the agent to check the documentation of the exact crate version.

Example request

First query the reqwest docs on how to send a POST with JSON and an authorization header. Then write the function for version 0.12.

MCP

Transport

stdio

Authentication

API key

Limitations

You need an OpenAI key in the `OPENAI_API_KEY` variable and network access, and the OpenAI API is unavailable from Russia. The embedding and answer models are fixed, and the documentation offers no setting to pick another. The author advises running the first build for a new crate, version or feature set by hand before connecting it to an agent. Embeddings cost money, though not much: for async-stripe with more than 5,000 pages they came to 0.18 US dollars. The repository was last updated in November 2025.

How to disable. Remove the server entry from the client configuration, for example from mcp_settings.json in Roo Code. The documentation cache lives in ~/.local/share/rustdocs-mcp-server/ and can be deleted by hand.

README in short

The author explains the motivation: assistants know syntax well but lag behind fast-moving crates because of their training cutoff. The server closes that gap with a targeted source and runs as an ordinary stdio MCP server. Compiled archives for Windows, Linux and macOS are on the releases page, and building from source is optional.