## Why
MCP tool hooks need to invoke model-hidden tools even when a subagent's cached server has not started. Their timeout must also cover server startup.
## What changed
- Let cached servers with allowed model-hidden tools remain dormant until called.
- Wait for the selected server when executing an MCP hook, leaving unrelated cached servers dormant, and apply the hook timeout to the entire operation.
- Capture tool namespace attribution after startup and retain it only while catalog revisions remain unchanged.
- Validate the server, environment, and tool filter before starting a server or capturing attribution.
## Testing
Extend integration coverage for cached subagent hooks under both startup readiness modes, startup timeouts without context injection, and namespace attribution for hook and token-budget context while keeping tools hidden from the model. Verify that a direct call starts a cached server whose tools are hidden from model exposure.
GitOrigin-RevId: 7a54b69aa2515722aeb925e03e1667bf63aa67ca
Charlie Marsh
cc44ffb3e2