Ferris
Ferris provides tools for inspecting Rust crate source code, helping your agent understand actual implementations rather than guessing at APIs.
Quick Reference
| What | How |
|---|---|
| Fetch crate sources | Agent uses crate_sources tool |
| Check workspace version | Automatic - defaults to version in your Cargo.toml |
| Specify version | Agent can request specific versions or semver ranges |
How It Works
When your agent needs to understand how a crate works, Ferris can fetch the source code directly from crates.io. This is useful when:
- Working with an unfamiliar crate
- Checking exact API signatures
- Understanding internal implementation details
- Finding usage examples in the crate’s own code
Tips
Encourage source checking - If Claude seems uncertain about a crate’s API or is making incorrect assumptions, prompt it to “check the sources” for that crate. This often leads to more accurate code.
Version awareness - Ferris automatically uses the crate version from your workspace’s Cargo.toml. If you need a different version, you can ask for a specific version or semver range.
Future Plans
Ferris is a work in progress. Future versions will include guidance on strong Rust coding patterns to help your agent write more idiomatic Rust.