Codex runs T3's MCP tools inside Code Mode. A blocking t3_thread_wait there is a nested call in a script, so the model keeps working around the wait and burns tokens. The Codex team suggested taking the wait out of Code Mode, like Codex's own wait and multi-agent tools.
Each Codex thread now gets T3's MCP server twice, with the same URL, auth, and timeout:
t3-code: every T3 tool except t3_thread_wait.t3code: only t3_thread_wait, with omit_tools_from = ["code_mode", "deferred"], so Codex exposes it as a direct tool.t3code is already a known T3 server alias, so tool display and "waiting" detection work unchanged. Codex versions without omit_tools_from ignore the key and behave as before.
Proof: real Codex 0.166.0 (codex exec, Code Mode on) against a mock Responses API and a mock T3 MCP server. In the captured model request, the old config has no direct T3 tool. The new config has a direct mcp__t3code → t3_thread_wait next to Codex's wait_agent and sleep. The other T3 tools stay where they were. The adapter config test pins the new shape.
Known limits:
~/.codex/config.toml defines a t3code server, or customizes T3's injected t3-code server, the per-thread override conflicts with or replaces it. T3 never creates either, and the same risk already exists for t3-code.evals/mcp-tool-use Codex simulator still offers the wait inside Code Mode.Rounds: 2
| Delegate | Round 1 | Round 2 |
|---|---|---|
| Claude Opus 5.5 | 8.5/10 | 9/10 |
| Muse Wonder Full | 9/10 | 9/10 |
| Codex GPT-6.1 Sol | 9/10 | 10/10 |
Made with Claude Opus 5.5 in Claude Code, running in T3 Code.
🤖 Generated with Claude Code
Added 1 commit
Verdict: Needs Human Approval
Macroscope's review found this PR requires human approval — Codex thread waits now run as direct blocking tool calls rather than nested Code Mode calls, automatically changing behavior for MCP-enabled threads. Human review is needed to confirm this default coordination behavior is intended.
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✅ Thread transfer remains within every enforced ceiling.
| Provider | Metric | Main baseline | This PR | Impact | PR ceiling | |
|---|---|---|---|---|---|---|
| Codex | Total thread wire | 5.0 KiB | 5.0 KiB | 0 B (0.0%) | 6.8 KiB | ✅ |
| Codex | Thread snapshot wire | 3.8 KiB | 3.8 KiB | 0 B (0.0%) | 4.9 KiB | ✅ |
| Codex | Live turn WebSocket wire | 1.3 KiB | 1.3 KiB | 0 B (0.0%) | 2.0 KiB | ✅ |
| Codex | Live turn WebSocket decoded | 21.6 KiB | 21.6 KiB | 0 B (0.0%) | 24.4 KiB | ✅ |
| Codex | Live turn messages | 2 | 2 | 0 (0.0%) | 8 | ✅ |
| Claude | Total thread wire | 5.0 KiB | 5.0 KiB | 0 B (0.0%) | 6.8 KiB | ✅ |
| Claude | Thread snapshot wire | 3.8 KiB | 3.8 KiB | 0 B (0.0%) | 4.9 KiB | ✅ |
| Claude | Live turn WebSocket wire | 1.3 KiB | 1.3 KiB | 0 B (0.0%) | 2.0 KiB | ✅ |
| Claude | Live turn WebSocket decoded | 21.9 KiB | 21.9 KiB | 0 B (0.0%) | 24.4 KiB | ✅ |
| Claude | Live turn messages | 2 | 2 | 0 (0.0%) | 8 | ✅ |
Baseline: 4a5251b · PR result: 78d529f · Source CI: success
10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.
Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.
Codex now receives T3 MCP settings through thread configuration. The settings register general tools as t3-code and t3_thread_wait as t3code. Tool presentation tests and documentation cover the aliases and configuration.
Changes: Codex T3 MCP registration
| Layer / File(s) | Summary |
|---|---|
Configure and verify T3 MCP registrations apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts, apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts, docs/orchestration-v2/orchestrator-mcp-server.md, packages/shared/src/t3McpToolPresentation.test.ts | Codex thread configuration uses the session endpoint, a 65-minute timeout, and an authorization header. It registers general tools under t3-code and t3_thread_wait under t3code. The documentation and tests cover the configuration and alias recognition. |
Estimated code review effort: 2 (Simple) | ~10 minutes
Change: Bug fix
| 1 | sequenceDiagram |
| 2 | participant Codex |
| 3 | participant CodexAdapterV2 |
| 4 | participant T3MCPServer |
| 5 | Codex->>CodexAdapterV2: Start, resume, or fork thread with MCP configuration |
| 6 | CodexAdapterV2->>T3MCPServer: Configure t3-code and t3code with session authorization |
| 7 | Codex->>T3MCPServer: Call t3_thread_wait through t3code |
Possibly related issues
pingdotgg/t3code#26120 — The issue describes the mismatch between launcher overrides and per-thread configuration that this change updates.Suggested reviewers: juliusmarminge, lnieuwenhuis
78d52Codex now calls the thread-wait tool directly instead of through Code Mode. A user who has hand-configured an MCP server named t3code could see thread start or resume fail, and this is already documented as a known limit. The change is otherwise mergeable.
| Check name | Status | Explanation |
|---|---|---|
| Title check | Passed | The title clearly identifies the primary change: Codex now calls t3_thread_wait directly instead of through Code Mode. |
| Description check | Passed | The description clearly explains the problem, implementation, verification evidence, known limits, and follow-up scope. It does not use the template headings or provide an explicit linked issue or mai… |
| Linked Issues check | Passed | Check skipped because no linked issues were found for this pull request. |
| Out of Scope Changes check | Passed | Check skipped because no linked issues were found for this pull request. |
Explanation
The description clearly explains the problem, implementation, verification evidence, known limits, and follow-up scope. It does not use the template headings or provide an explicit linked issue or maintainer approval, but the content is mostly complete.
apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts-1373-1373: 1
1373-1373: External image Major · Security & Privacy · Quick winExternal image Unverified finding Verification ran but could not confirm this finding. It is shown for review, not as a verified issue.
Preserve configured tool restrictions.
A user’s
t3-code.disabled_toolslist is replaced by this list. Previously disabled tools, such ast3_thread_send, become available to the agent. The newt3coderegistration can also exposet3_thread_waitwhen the user’st3-code.enabled_toolsexcludes it. Preserve the effective allow and deny lists across both registrations. (raw.githubusercontent.com)
c7b04025-14d8-4a96-bd21-8f65a2abfd3bReviewing files that changed from the base of the PR and between 4a5251b1c4b867ad2d89bf59d7a062ca8c40f2a6 and 78d529fd17f390fe5199bb545ba0d147f9b4b277.
apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.tsapps/server/src/orchestration-v2/Adapters/CodexAdapterV2.tsdocs/orchestration-v2/orchestrator-mcp-server.mdpackages/shared/src/t3McpToolPresentation.test.tsIncluded review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 7 remain after this review.