codex exec session schema does not expose MCP tools even though `codex mcp list` shows server enabled

What version of Codex CLI is running?

codex-cli 0.120.0

What subscription do you have?

200$ PRO

Which model were you using?

gpt-5.4

What platform is your computer?

Darwin 25.4.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

iTerm2

What issue are you seeing?

I can confirm that my MCP server is registered and enabled:

codex mcp list
-> code-review-graph code-review-graph serve enabled

However, in a real codex exec --json session, the model-visible tool schema does not include any functions.mcp__code_review_graph__* tools.

Observed behavior:

• MCP server is enabled in config and visible in codex mcp list
• MCP server itself can start (code-review-graph serve)
• But the actual codex exec session does not expose the MCP tools to the model
• The model explicitly reports that no code-review-graph-related tools are available in the current session

Important clarification:

• resources / resourceTemplates being empty is expected here because this MCP server is tool-only
• The problem is specifically that tools are not injected into the exec session schema

Question:
Is codex exec expected to expose external MCP tools configured in ~/.codex/config.toml?
If yes, what conditions can cause an enabled MCP server to be omitted from the exec session tool schema?

What steps can reproduce the bug?

I can confirm that my MCP server is registered and enabled:

codex mcp list
-> code-review-graph code-review-graph serve enabled

However, in a real codex exec --json session, the model-visible tool schema does not include any functions.mcp__code_review_graph__* tools.

Observed behavior:

• MCP server is enabled in config and visible in codex mcp list
• MCP server itself can start (code-review-graph serve)
• But the actual codex exec session does not expose the MCP tools to the model
• The model explicitly reports that no code-review-graph-related tools are available in the current session

Important clarification:

• resources / resourceTemplates being empty is expected here because this MCP server is tool-only
• The problem is specifically that tools are not injected into the exec session schema

Question:
Is codex exec expected to expose external MCP tools configured in ~/.codex/config.toml?
If yes, what conditions can cause an enabled MCP server to be omitted from the exec session tool schema?

What is the expected behavior?

_No response_

Additional information

_No response_