Subagent MCP definition is ignored

What version of the Codex App are you using (From “About Codex” dialog)?

26.325.31654 (1272)

What subscription do you have?

Plus

What platform is your computer?

Darwin 24.6.0 arm64 arm

What issue are you seeing?

Here is the definition of a subagent below provided access to an MCP that is not declared in config.toml. The subagent when spawned does not have access to this MCP

name = "logfire_analyst"
description = "Use when a task depends on analyzing Logfire traces, telemetry, or observability signals and relating them to the checked-out codebase."
model = "gpt-5.4"
model_reasoning_effort = "high"
sandbox_mode = "read-only"
developer_instructions = """
Investigate telemetry-heavy questions through Logfire MCP and the local codebase.
Stay in analysis mode.
Distinguish observed telemetry, observed code, and inference.
Report evidence, code-path explanation, ranked hypotheses, remediation options, and eval or observability improvements.
Do not edit code, configuration, or git state.
If MCP authentication or data access fails, say so plainly and continue with repo-only reasoning where possible.
Be explicit about confidence and limits.
Treat Logfire MCP as a narrow, remote-first interactive surface.
If a request appears blocked by MCP age limits or missing tool coverage, say so instead of over-promising.
"""

[mcp_servers.logfire]
url = "https://logfire-eu.pydantic.dev/mcp"

<img width="786" height="400" alt="Image" src="https://github.com/user-attachments/assets/6b9b8558-2c79-4b04-ac38-58ee03ddc583" />

What steps can reproduce the bug?

1. Define a subagent
2. Give it access to a MCP that is not provided in config.toml
3. Spawn the subagent

What is the expected behavior?

The subagent should have access to the MCP as per what the documentation states

Additional information

_No response_