rspeek

Inspect type definitions from Rust crate source code without building docs.

Searches dependency crates and workspace member crates for structs, enums, unions, traits, type aliases, constants, statics, and functions — including integration tests in tests/.

Installation

cargo install --path .

Kiro CLI setup

Generate a steering file so the Kiro CLI knows how to use rspeek:

rspeek --llm-help > ~/.kiro/steering/rspeek.md

Usage

Run from any directory containing a Cargo.toml.

rspeek <crate>                    List public items in a crate
rspeek <Item>                     Search all crates for an item
rspeek <crate> <Item>             Search within one crate
rspeek <crate>::<path>::<Item>    Match by module path

Flags

• --json — structured JSON output (for LLMs and scripts)
• --impls — include impl blocks for matched types
• --signature — show only signatures (no function/method bodies)
• --api — shorthand for --signature --impls (type API at a glance)
• --crate-version <VERSION> — filter to a specific crate version (accepts v prefix)
• --llm-help — extended usage documentation for LLM tool integration

Examples

# List public items in a crate
rspeek anyhow

# Find a type across all dependencies
rspeek Error

# Find a specific type in a crate
rspeek anyhow Error
rspeek anyhow::Error              # equivalent

# Match by module path
rspeek serde::de::Visitor
rspeek cargo_metadata::dependency::DependencyKind

# JSON output
rspeek --json anyhow Error

# Include impl blocks
rspeek --impls anyhow Error

# Signatures only (no function bodies)
rspeek --signature anyhow Error

# Signatures for type + impl methods
rspeek --signature --impls anyhow Error

# Pin a specific crate version
rspeek --crate-version 0.29.0 nix kill

Output

Single match — full markdown with doc comments, source path, line number, crate version, and original source:

## `Error` (struct)
**Source:** `/home/user/.cargo/registry/src/.../anyhow-1.0.102/src/lib.rs:288`
**Crate:** `anyhow` v1.0.102

```rust
/// The `Error` type, a wrapper around a dynamic error type.
pub struct Error {
    inner: Own<ErrorImpl>,
}
```

Multiple matches — summary list with qualified paths and locations. When the same item exists in multiple versions of a crate, only the newest is shown with the other versions noted:

Found 7 matches for `Error`:

- struct `anyhow::Error` v1.0.102 at /home/user/.cargo/.../lib.rs:288
- enum `cargo_metadata::errors::Error` v0.23.1 at /home/user/.cargo/.../errors.rs:6
- struct `serde_json::error::Error` v1.0.149 at /home/user/.cargo/.../error.rs:15 (also in v1.0.140, v1.0.145)

Crate overview — source path, dependencies, and item listing:

## `serde_json` v1.0.149
**Source:** `/home/user/.cargo/registry/src/.../serde_json-1.0.149/src`

**Dependencies:** itoa, memchr, serde, serde_core, zmij

**Workspace members (not yet deps):** my-utils, my-core

Public items:

- struct `de::Deserializer`
- fn `de::from_reader`
- fn `de::from_slice`
- fn `de::from_str`
- struct `error::Error`
- enum `value::Value`

Usage: `rspeek serde_json <Item>`

For workspace members, all items are shown (not just public). Dependencies and Workspace members (not yet deps) help you discover what's already usable and what can be added with a one-line Cargo.toml edit.

JSON output

--json returns an array of objects:

[{
  "name": "Error",
  "kind": "struct",
  "module_path": "",
  "file": "/path/to/src/lib.rs",
  "start_line": 288,
  "end_line": 392,
  "crate_name": "anyhow",
  "crate_version": "1.0.102",
  "source": "pub struct Error { ... }",
  "impls": [{"trait_name": null, "file": "...", "start_line": 19, "end_line": 670, "source": "..."}],
  "other_versions": ["1.0.98", "1.0.100"]
}]

The impls field is only present when --impls is used. The other_versions field is only present when older versions were collapsed.

Errors are also JSON when --json is set:

{"error": "no item `Contxt` found in dependencies", "suggestions": ["Context"]}

Did you mean?

When no match is found, rspeek suggests similar names using Levenshtein distance and prefix matching (like rustc):

Error: no item `Contxt` found in dependencies

did you mean `Context`?

LLM Integration

Use --llm-help for extended usage documentation suitable for tool descriptions.

Scope

• Dependency crates: searches src/, public items only
• Workspace member crates: searches src/ and tests/, all items (including tests)

Limitations

• Only finds items defined as regular Rust syntax (struct, enum, union, trait, type, fn, const, static)
• Macro bodies are parsed for item definitions (e.g., syn's ast_struct!), but procedural macros and complex macro_rules! patterns are not expanded
• Re-exports: pub use within a crate are followed; glob re-exports and cross-crate re-exports are not