codex/codex-rs/tools

codex-tools

codex-tools is the shared support crate for building, adapting, and executing model-visible tools outside codex-core.

Today this crate owns the host-facing tool models and helpers that no longer need to live in core/src/tools/spec.rs or core/src/client_common.rs:

• aggregate host models such as ToolSpec, ConfiguredToolSpec, LoadableToolSpec, ResponsesApiNamespace, and ResponsesApiNamespaceTool
• host discovery models used while assembling tool sets, including discoverable-tool models and request-plugin-install helpers
• host adapters such as schema sanitization, MCP/dynamic conversion, code-mode augmentation, and image-detail normalization
• shared executable-tool contracts such as ToolExecutor, ToolCall, and ToolOutput

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 host-side tool machinery that is shared by multiple consumers, for example:

• host-visible aggregate tool models
• tool-set planning and discovery helpers
• MCP and dynamic-tool adaptation into Responses API shapes
• code-mode compatibility shims that do not depend on codex-core
• other narrowly scoped host utilities 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. Keep extension-owned executable-tool authoring in codex-extension-api.
2. Move host-side planning/adaptation helpers here when they no longer need to stay coupled to codex-core.
3. Leave compatibility-sensitive adapters in codex-core while downstream call sites are updated.
4. Only extract higher-level host infrastructure after the crate boundaries are clear and independently testable.

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.