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

3.0 KiB

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:
#[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.