> Map Rust crates for AI agents: structs, traits, impl blocks, use trees and macro calls, framework detection from Cargo.toml and who calls what.

Source: https://callgraph.eu/rust/

# Rust call graph and impact analysis for AI agents

callgraph parses `.rs` files with [syn](https://github.com/dtolnay/syn) and gives your agent modules, structs, traits and `impl` blocks with exact line ranges, every call sorted by category, and who calls a function across the crate — without reading the file.

[Install](https://callgraph.eu/#install) [Use it over MCP](https://callgraph.eu/mcp/)

## What callgraph extracts from Rust

- The file module, inline `mod`s, `struct`s, `enum`s, `union`s and `trait`s (with supertraits).

- The methods of `impl` blocks go to their type; trait implementations are listed under `implements`.

- Functions with visibility (`pub`, `pub(crate)`…), `async`, parameters and return type; `macro_rules!` macros.

- Fields, `const` / `static` items, type aliases and enum variants.

- Flattened `use` trees, path / method / macro calls, `if` / `match` branches, string literals (also in attributes such as `#[get("/users/{id}")]`).

## Framework awareness: axum, actix-web, tokio…

The framework comes from the nearest `Cargo.toml` above the file: the first known dependency, in this order — bevy, tauri, leptos, dioxus, yew, axum, actix-web, rocket, warp, poem, diesel, sqlx, sea-orm, clap, tokio, async-std, serde. Calls into known framework crates are labelled `framework_use`, and [`profile`](https://callgraph.eu/profile/) recognises a Rust web architecture.

| Category | When |
|---|---|
| `internal_helper` | the file's own types, functions and methods (`self.x()`, `Self::x()`) |
| `module_use` | another module of the crate (`crate::`, `super::`), shown as `module::fn` / `Type::fn` |
| `native_rust` | std / core / alloc, the prelude and common std methods |
| `framework_use` | known framework crates (axum, tower, hyper, actix_web, rocket, tokio, serde, clap, diesel, sqlx, bevy…) |
| `package_use` | another crate (an external dependency) |
| `macro_use` | every macro call; the macro is not expanded |
| `external_call` | a local variable or closure, or a method on an unknown receiver (`?::name`) |

## Commands

```
CG=~/.claude/skills/callgraph/callgraph.sh
bash $CG --project myapp src/api/users.rs              # outline: struct/impl/trait, fns with line ranges
bash $CG --project myapp src/api/users.rs --format api # pub items, incl. the pub fn of impl blocks
bash $CG --project myapp src --const MAX_ITEMS         # const / static (also Type::CONST): definition + uses
```

`--const` also shows where a name is passed on, for example `pub use state::{CheckState, STATE_FILE};` appears as `[re-export] state::STATE_FILE`.

## Who calls this Rust function?

```
bash $CG --project myapp src --grep 'Repo::find'                # crate-internal: Type::fn / module::fn
bash $CG --project myapp src --grep '(^|::|\.|->)find$'         # every call of the name
bash $CG --project myapp src --grep 'Repo::find' --depth 3      # callers of callers
```

For a method called on a value (`x.load()`) callgraph works out the type of `x` in the simple, reliable cases: a parameter type (`x: &Repo`, `Box` / `Rc` / `Arc`, an extractor like `State(s): State<App>`), `let x = Repo::new()`, a struct literal, `self`, or a field of your own struct (`self.repo.load()`). Then the call shows up as `Repo::load`. When the type can't be worked out, it is kept as `?::load`, and a `Repo::load` search still lists it, marked as uncertain — instead of silently missing it.

## Limits

- Macros are not expanded: code generated by derive, attribute or function-like macros is not visible.

- Type inference is deliberately simple: return types and chained calls (`a.b().c()`) get no type.

- `cfg` attributes are not evaluated: every branch, such as `#[cfg(test)] mod tests`, is included.

- A file with a syntax error yields only the file container and a warning.

- The walker does not skip `target/`; point callgraph at your `src` folder.

## Related

[

### locate

Ranked files to start a task with.

](https://callgraph.eu/locate/) [

### Project profile

Architecture and layers of a crate.

](https://callgraph.eu/profile/) [

### MCP server

The same queries in any MCP client.

](https://callgraph.eu/mcp/) [

### Swift / SwiftUI

Another native language callgraph maps.

](https://callgraph.eu/swift/)