Files
codex/codex-rs/tools/README.md
Michael Bolin bc53d42fd9 codex-tools: extract tool spec models (#16047)
## Why

This continues the `codex-tools` migration by moving another passive
tool-definition layer out of `codex-core`.

After `ResponsesApiTool` and the lower-level schema adapters moved into
`codex-tools`, `core/src/client_common.rs` was still owning `ToolSpec`
and the web-search request wire types even though they are serialized
data models rather than runtime orchestration. Keeping those types in
`codex-core` makes the crate boundary look smaller than it really is and
leaves non-runtime tool-shape code coupled to core.

## What changed

- moved `ToolSpec`, `ResponsesApiWebSearchFilters`, and
`ResponsesApiWebSearchUserLocation` into
`codex-rs/tools/src/tool_spec.rs`
- added focused unit tests in `codex-rs/tools/src/tool_spec_tests.rs`
for:
  - `ToolSpec::name()`
  - web-search config conversions
  - `ToolSpec` serialization for `web_search` and `tool_search`
- kept `codex-rs/tools/src/lib.rs` exports-only by re-exporting the new
module from `lib.rs`
- reduced `core/src/client_common.rs` to a compatibility shim that
re-exports the extracted tool-spec types for current core call sites
- updated `core/src/tools/spec_tests.rs` to consume the extracted
web-search types directly from `codex-tools`
- updated `codex-rs/tools/README.md` so the crate contract reflects that
`codex-tools` now owns the passive tool-spec request models in addition
to the lower-level Responses API structs

## Test plan

- `cargo test -p codex-tools`
- `cargo test -p codex-core --lib tools::spec::`
- `cargo test -p codex-core --lib client_common::`
- `just fix -p codex-tools -p codex-core`
- `just argument-comment-lint`

## References

- #15923
- #15928
- #15944
- #15953
- #16031
2026-03-28 13:37:00 -07:00

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Markdown

# codex-tools
`codex-tools` is intended to become the home for tool-related code that is
shared across multiple crates and does not need to stay coupled to
`codex-core`.
Today this crate is intentionally small. It currently owns the shared tool
schema and Responses API tool primitives that no longer need to live in
`core/src/tools/spec.rs` or `core/src/client_common.rs`:
- `JsonSchema`
- `AdditionalProperties`
- `ToolDefinition`
- `ToolSpec`
- `ResponsesApiTool`
- `FreeformTool`
- `FreeformToolFormat`
- `ToolSearchOutputTool`
- `ResponsesApiWebSearchFilters`
- `ResponsesApiWebSearchUserLocation`
- `ResponsesApiNamespace`
- `ResponsesApiNamespaceTool`
- `parse_tool_input_schema()`
- `parse_dynamic_tool()`
- `parse_mcp_tool()`
- `mcp_call_tool_result_output_schema()`
- `tool_definition_to_responses_api_tool()`
- `dynamic_tool_to_responses_api_tool()`
- `mcp_tool_to_responses_api_tool()`
- `mcp_tool_to_deferred_responses_api_tool()`
That extraction is the first step in a longer migration. The goal is not to
move all of `core/src/tools` into this crate in one shot. Instead, the plan is
to peel off reusable pieces in reviewable increments while keeping
compatibility-sensitive orchestration in `codex-core` until the surrounding
boundaries are ready.
## Vision
Over time, this crate should hold tool-facing primitives that are shared by
multiple consumers, for example:
- schema and spec data models
- tool input/output parsing helpers
- tool metadata and compatibility shims that do not depend on `codex-core`
- other narrowly scoped utility code that multiple crates need
The corresponding non-goals are just as important:
- do not move `codex-core` orchestration here prematurely
- do not pull `Session` / `TurnContext` / approval flow / runtime execution
logic into this crate unless those dependencies have first been split into
stable shared interfaces
- do not turn this crate into a grab-bag for unrelated helper code
## Migration approach
The expected migration shape is:
1. Move low-coupling tool primitives here.
2. Switch non-core consumers to depend on `codex-tools` directly.
3. Leave compatibility-sensitive adapters in `codex-core` while downstream
call sites are updated.
4. Only extract higher-level tool infrastructure after the crate boundaries are
clear and independently testable.
That means it is normal for `codex-core` to temporarily re-export types or
helpers from `codex-tools` during the transition.
## Crate conventions
This crate should start with stricter structure than `core/src/tools` so it
stays easy to grow:
- `src/lib.rs` should remain exports-only.
- Business logic should live in named module files such as `foo.rs`.
- Unit tests for `foo.rs` should live in a sibling `foo_tests.rs`.
- The implementation file should wire tests with:
```rust
#[cfg(test)]
#[path = "foo_tests.rs"]
mod tests;
```
If this crate starts accumulating code that needs runtime state from
`codex-core`, that is a sign to revisit the extraction boundary before adding
more here.