Bevy Manual MCP

bevy-manual-mcp

This MCP was designed by a human and built using AI tools to increase development speed.

Bevy is a fast-moving project that changes with every release. Its documentation is large and scattered, so finding an answer that actually matches your version often means digging through rustdoc signatures, the Bevy Book, migration guides, release notes and runnable examples - and still landing on something written for a different release. This server tries its best to remove that friction.

You ask your agent a question and it answers from knowledge pinned to the exact Bevy version your project is using.

Key points:

• MCP Registry name: mcp-name: io.github.kinkirill/bevy-manual-mcp
• Native. Rust, stdio MCP, no Node or npm in the user's path. (The initial version of this MCP was written in JS and later in TS.)
• Small. A 33 MB bundle per Bevy version (125 MB corpus + 15 MB tantivy index, zstd-compressed).
• Fast. ~10 ms cold start, 22–30 ms concept queries, sub-millisecond exact lookups.
• Honest. Every tool says what it cannot do: bevy_validate_systems is a syntax-level linter, compatibility can be "unknown", and missing metadata is reported as missing.

Install

cargo install bevy-manual-mcp

Requires a Rust toolchain. There is no prebuilt binary matrix and no npm shim.

The server starts answering immediately. If the detected Bevy version has no installed index, it downloads the prebuilt bundle in the background (progress on stderr) and reloads the index when the install completes. To install it explicitly before starting the server:

bevy-manual-mcp fetch-index 0.20.1
bevy-manual-mcp status

Index releases are per Bevy minor (v0.20); an exact-patch corpus is used when present, otherwise the same minor's newest corpus answers for the patch. Status, search results and resources report both the project version and the corpus version that actually supplied the data. BEVY_MCP_OFFLINE=1 disables all downloads, including the background fetch.

Use it

The bare command is the MCP server (stdio), exactly as MCP clients launch it.

bevy-manual-mcp                 # serve MCP over stdio
bevy-manual-mcp serve           # explicit form
bevy-manual-mcp --help
bevy-manual-mcp status          # detected version, corpus state, paths
bevy-manual-mcp versions        # installed corpora
bevy-manual-mcp search "system ordering"
bevy-manual-mcp lookup Query::iter --json

MCP client configuration

Most clients only need a command:

{
  "mcpServers": {
    "bevy-manual-mcp": {
      "type": "stdio",
      "command": "bevy-manual-mcp",
      "env": {
        "BEVY_PROJECT_ROOT": "/path/to/your/bevy/game"
      }
    }
  }
}

BEVY_PROJECT_ROOT is optional if the client's working directory is the Cargo project; the version is read from Cargo.lock first and Cargo.toml second.

Tools

bevy_validate_systems does not type-check and cannot decide Bevy runtime panics; it recognises the B0001/B0002 access patterns and says when its analysis is incomplete. bevy_generate_plugin reports compile_verified: false because no compiler runs. bevy_ecosystem_compat is offline-only and returns compatible: "unknown" for requirement operators it does not evaluate.

Resources

The server also exposes bevy:// resources and templates:

bevy://index/versions
bevy://api/<version>/<full::path>
bevy://kind/<version>/<kind>
bevy://module/<version>/<module>
bevy://crate/<version>/<subcrate>
bevy://owner/<version>/<Type>
bevy://doc/<version>/<rustdoc file>

Listings page at 50 items with query-bound cursors; reads open the requested version on demand.

Configuration

File (bevy-mcp.config.json), environment and defaults combine in that order; environment variables win.

The config file additionally accepts a corpora array for plugin corpora:

{
  "corpora": [
    { "crate": "bevy_egui", "version": "0.43.1" },
    { "crate": "bevy_rapier3d", "auto": true }
  ]
}

Plugin corpora live under data/corpora/<crate>/<version>/ and are built with the normal build command.

Rebuilding indexes

# From a local `cargo doc` tree (or a docs.rs mirror)
bevy-manual-mcp build --doc-dir target/doc

# Canonical NDJSON input
bevy-manual-mcp build --records records.ndjson --out data/versions/0.20.0

# Release bundle + manifest
bevy-manual-mcp build --doc-dir ~/.cache/bevy-mcp/bevy-0.20.0 \
  --pack dist/bevy-0.20.0-fmt1.tar.zst \
  --manifest dist/index-manifest.json

A full 0.20.0 rebuild from 8,665 rustdoc pages takes ~30 s in release mode and produces exactly the canonical corpus: 253,196 records, 653,264 symbol keys, 15.2 MB tantivy index. See GETTING-API-DOCS.md and HOW-IT-WORKS.md.

Development

See docs/DEVELOPING.md for the layout, tests, index rebuilds and release process.

License

MIT. Vendored Bevy metadata and website prose are covered in docs/THIRD-PARTY-NOTICES.md.