[Bug] SendMessage tool unavailable despite being documented for agent continuation

Bug Description
Bug Description
SendMessage tool referenced in Agent tool description but not available

The Agent tool description states: "To continue a previously spawned agent, use SendMessage with the agent's ID or name as the to field — that resumes it with full context."

Each agent invocation also returns an agentId in its result, explicitly prompting: "use SendMessage with to: '' to continue this agent".

However, SendMessage is not present in the available tool list, not in the deferred tool list, and cannot be found via ToolSearch. Calling it would fail.

Impact: Agents cannot be resumed or continued. Every follow-up requires a full cold-start via a new Agent call, defeating the purpose of the agentId return value and making multi-turn agent
workflows significantly more expensive in tokens.

Expected: SendMessage is available as a tool when an agentId has been returned by a prior Agent call.

Actual: SendMessage is not available. The agentId values returned by agents are unusable.

Environment Info

• Platform: darwin

-Terminal: all, platform agnostic

• Version: 2.1.98
• Feedback ID: 0e66e490-b063-4ff5-a275-c839a99a6067