## Summary
- Thread `agent_max_threads` into `ToolsConfig` and
`SpawnAgentToolOptions`.
- Render the configured `max_concurrent_threads_per_session` value in
the MultiAgentV2 `spawn_agent` description.
- Cover the description text in `codex-tools` unit tests and
`codex-core` tool spec tests.
## Validation
- `just fmt`
- `cargo test -p codex-tools`
- `cargo test -p codex-core spawn_agent_description`
- `git diff --check`
## Notes
- `cargo test -p codex-core` was also attempted, but unrelated
environment-sensitive tests failed with the active local environment.
Examples: approvals reviewer defaults observed `AutoReview` instead of
`User`, request-permissions event tests did not emit events, and
proxy-env tests saw `http://127.0.0.1:50604` from the active proxy
environment.
Co-authored-by: Codex <noreply@openai.com>
Deferred dynamic tools need to round-trip a namespace so a tool returned
by `tool_search` can be called through the same registry key that core
uses for dispatch.
This change adds namespace support for dynamic tool specs/calls,
persists it through app-server thread state, and routes dynamic tool
calls by full `ToolName` while still sending the app the leaf tool name.
Deferred dynamic tools must provide a namespace; non-deferred dynamic
tools may remain top-level.
It also introduces `LoadableToolSpec` as the shared
function-or-namespace Responses shape used by both `tool_search` output
and dynamic tool registration, so dynamic tools use the same wrapping
logic in both paths.
Validation:
- `cargo test -p codex-tools`
- `cargo test -p codex-core tool_search`
---------
Co-authored-by: Sayan Sisodiya <sayan@openai.com>
## Summary
- Normalize deferred MCP and dynamic tools into `ToolSearchEntry` values
before constructing `ToolSearchHandler`.
- Move the tool-search entry adapter out of `tools/handlers` and into
`tools/tool_search_entry.rs` so the handlers directory stays focused on
handlers.
- Keep `ToolSearchHandler` operating over one generic entry list for
BM25 search, namespace grouping, and per-bucket default limits.
## Why
Follow-up cleanup for #17849. The dynamic tool-search support made the
handler juggle source-specific MCP and dynamic tool lists, index
arithmetic, output conversion, and namespace emission. This keeps source
adaptation outside the handler so the search loop itself is smaller and
source-agnostic.
## Validation
- `just fmt`
- `cargo test -p codex-core tools::handlers::tool_search::tests`
- `git diff --check`
- `cargo test -p codex-core` currently fails in unrelated
`plugins::manager::tests::list_marketplaces_ignores_installed_roots_missing_from_config`;
rerunning that single test fails the same way at
`core/src/plugins/manager_tests.rs:1692`.
---------
Co-authored-by: pash <pash@openai.com>
## Summary
- hide deferred MCP/app nested tool descriptions from the `exec` prompt
in code mode
- add short guidance that omitted nested tools are still available
through `ALL_TOOLS`
- cover the code_mode_only path with an integration test that discovers
and calls a deferred app tool
## Motivation
`code_mode_only` exposes only top-level `exec`/`wait`, but the `exec`
description could still include a large nested-tool reference. This
keeps deferred nested tools callable while avoiding that prompt bloat.
## Tests
- `just fmt`
- `just fix -p codex-code-mode`
- `just fix -p codex-tools`
- `cargo test -p codex-code-mode
exec_description_mentions_deferred_nested_tools_when_available`
- `cargo test -p codex-tools
create_code_mode_tool_matches_expected_spec`
- `cargo test -p codex-core
code_mode_only_guides_all_tools_search_and_calls_deferred_app_tools`
## Summary
- Ensure direct namespaced MCP tool groups are emitted with a non-empty
namespace description even when namespace metadata is missing or blank.
- Add regression coverage for missing MCP namespace descriptions.
## Cause
Latest `main` can serialize a direct namespaced MCP tool group with an
empty top-level `description`. The namespace description path used
`unwrap_or_default()` when `tool_namespaces` did not include metadata
for that namespace, so the outbound Responses API payload could contain
a tool like `{"type":"namespace","description":""}`. The Responses API
rejects that because namespace tool descriptions must be a non-empty
string.
## Fix
- Add a fallback namespace description: `Tools in the <namespace>
namespace.`
- Preserve provided namespace descriptions after trimming, but treat
blank descriptions as missing.
### Issue I am seeing
This is what I am seeing on the local build.
<img width="1593" height="488" alt="Screenshot 2026-04-15 at 10 55 55
AM"
src="https://github.com/user-attachments/assets/bab668ba-bf17-4c71-be4e-b102202fce57"
/>
---------
Co-authored-by: Sayan Sisodiya <sayan@openai.com>
stacked on #17402.
MCP tools returned by `tool_search` (deferred tools) get registered in
our `ToolRegistry` with a different format than directly available
tools. this leads to two different ways of accessing MCP tools from our
tool catalog, only one of which works for each. fix this by registering
all MCP tools with the namespace format, since this info is already
available.
also, direct MCP tools are registered to responsesapi without a
namespace, while deferred MCP tools have a namespace. this means we can
receive MCP `FunctionCall`s in both formats from namespaces. fix this by
always registering MCP tools with namespace, regardless of deferral
status.
make code mode track `ToolName` provenance of tools so it can map the
literal JS function name string to the correct `ToolName` for
invocation, rather than supporting both in core.
this lets us unify to a single canonical `ToolName` representation for
each MCP tool and force everywhere to use that one, without supporting
fallbacks.
- [x] Expand tool search to custom MCPs.
- [x] Rename several variables/fields to be more generic.
Updated tool & server name lifecycles:
**Raw Identity**
ToolInfo.server_name is raw MCP server name.
ToolInfo.tool.name is raw MCP tool name.
MCP calls route back to raw via parse_tool_name() returning
(tool.server_name, tool.tool.name).
mcpServerStatus/list now groups by raw server and keys tools by
Tool.name: mod.rs:599
App-server just forwards that grouped raw snapshot:
codex_message_processor.rs:5245
**Callable Names**
On list-tools, we create provisional callable_namespace / callable_name:
mcp_connection_manager.rs:1556
For non-app MCP, provisional callable name starts as raw tool name.
For codex-apps, provisional callable name is sanitized and strips
connector name/id prefix; namespace includes connector name.
Then qualify_tools() sanitizes callable namespace + name to ASCII alnum
/ _ only: mcp_tool_names.rs:128
Note: this is stricter than Responses API. Hyphen is currently replaced
with _ for code-mode compatibility.
**Collision Handling**
We do initially collapse example-server and example_server to the same
base.
Then qualify_tools() detects distinct raw namespace identities behind
the same sanitized namespace and appends a hash to the callable
namespace: mcp_tool_names.rs:137
Same idea for tool-name collisions: hash suffix goes on callable tool
name.
Final list_all_tools() map key is callable_namespace + callable_name:
mcp_connection_manager.rs:769
**Direct Model Tools**
Direct MCP tool declarations use the full qualified sanitized key as the
Responses function name.
The raw rmcp Tool is converted but renamed for model exposure.
**Tool Search / Deferred**
Tool search result namespace = final ToolInfo.callable_namespace:
tool_search.rs:85
Tool search result nested name = final ToolInfo.callable_name:
tool_search.rs:86
Deferred tool handler is registered as "{namespace}:{name}":
tool_registry_plan.rs:248
When a function call comes back, core recombines namespace + name, looks
up the full qualified key, and gets the raw server/tool for MCP
execution: codex.rs:4353
**Separate Legacy Snapshot**
collect_mcp_snapshot_from_manager_with_detail() still returns a map
keyed by qualified callable name.
mcpServerStatus/list no longer uses that; it uses
McpServerStatusSnapshot, which is raw-inventory shaped.
Allow multi_agent_v2 features to have its own temporary configuration
under `[features.multi_agent_v2]`
```
[features.multi_agent_v2]
enabled = true
usage_hint_enabled = false
usage_hint_text = "Custom delegation guidance."
hide_spawn_agent_metadata = true
```
Absent `usage_hint_text` means use the default hint.
```
[features]
multi_agent_v2 = true
```
still works as the boolean shorthand.
## Summary
- make `CODEX_EXEC_SERVER_URL=none` map to an explicit disabled
environment mode instead of inferring from a missing URL
- expose environment capabilities (`exec_enabled`, `filesystem_enabled`)
so tool building can gate behavior explicitly and future
multi-environment work has a clearer seam
- suppress env-backed tools when the relevant capability is unavailable,
including exec tools, `js_repl`, `apply_patch`, `list_dir`, and
`view_image`
- keep handler/runtime backstops so disabled environments still reject
execution if a tool path somehow bypasses registration
## Testing
- `just fmt`
- `cargo test -p codex-exec-server`
- `cargo test -p codex-tools
disabled_environment_omits_environment_backed_tools`
- `cargo test -p codex-tools
environment_capabilities_gate_exec_and_filesystem_tools_independently`
- remote devbox Bazel build via `codex-applied-devbox`:
`//codex-rs/cli:cli`
## Why
#16513 moved pure tool-registry planning into `codex-tools`, but much of
the corresponding spec/feature-gating coverage still lived in
`codex-core`. That leaves the tests for planner behavior in the crate
that no longer owns that logic and makes the next extraction steps
harder to review.
## What
Move the planner-only `spec_tests.rs` coverage into
`codex-rs/tools/src/tool_registry_plan_tests.rs` and wire it up from
`codex-rs/tools/src/tool_registry_plan.rs` using the crate-local `#[path
= "tool_registry_plan_tests.rs"] mod tests;` pattern.
The `codex-core` test file now keeps the core-side integration checks:
router-visible model tool lists, namespaced handler alias registration,
shell adapter behavior, and MCP schema edge cases that still exercise
the `core` binding layer.
## Verification
- `cargo test -p codex-tools`
- `cargo test -p codex-core tools::spec::tests`
## Why
This is a larger step in the `codex-core` -> `codex-tools` migration
called out in `AGENTS.md`.
`codex-rs/core/src/tools/spec.rs` had become mostly pure tool-spec
assembly plus handler registration. That made it hard to move more of
the tool-definition layer into `codex-tools`, because the runtime
binding and the crate-independent planning logic were still interleaved
in one function.
Splitting those concerns gives `codex-tools` ownership of the
declarative registry plan while keeping `codex-core` responsible for
instantiating concrete handlers.
## What Changed
- Add a `codex-tools` registry-plan layer in
`codex-rs/tools/src/tool_registry_plan.rs` and
`codex-rs/tools/src/tool_registry_plan_types.rs`.
- Move feature-gated tool-spec assembly, MCP/dynamic tool conversion,
tool-search aliases, and code-mode nested-plan expansion into
`codex-tools`.
- Keep `codex-rs/core/src/tools/spec.rs` as the core-side adapter that
maps each planned handler kind to concrete runtime handler instances.
- Update `spec_tests.rs` to import the moved `codex_tools` symbols
directly instead of relying on top-level `spec.rs` re-exports.
This is intended to be a straight refactor with no behavior change and
no new test surface.
## Verification
- `cargo test -p codex-tools`
- `cargo test -p codex-core tools::spec::tests`
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/16513).
* #16521
* __->__ #16513
Curtis 'Fjord' HawthorneandGitHub
Vivian FangandGitHub
Matthew ZengandGitHub
pakrym-oaiandGitHub
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