System-tool definitions are authoring contracts. Their presence does not establish working call transfers, keypad tones, language detection, voicemail detection, or procedure execution in a live conversation.
Available contract categories
A system-tool definition usestype: "system" and a params object whose system_tool_type selects the action contract.
The agent prompt’s
built_in_tools field describes built-in tool configuration. Follow the current agent schema for its exact shape. Do not treat a system-tool name as an ordinary workspace tool ID.
Prepare the behavior
1
Write the action condition
State when the action is appropriate. For a handoff, describe the request that requires another handler and what information should be retained in a summary.
2
Review required resources
Transfer tools require their own destination configuration. Procedure tools reference procedures. Review those resources independently; a destination field does not provision a phone number or grant access to another agent.
3
Save a configuration draft
Preserve the complete snapshot through versions and drafts. Read the saved built-in configuration back and compare it with your intended conditions.
4
Prepare an unavailable-action response
Write a response the agent should use if a transfer or other action cannot complete. Do not tell a user that an action succeeded without a verified result.
Frequently asked questions
Does end_call prove that outbound calls are available?
Does end_call prove that outbound calls are available?
No. Conversation controls and channel readiness are separate. Review telephony availability before planning phone workflows.
Does a knowledge tool make retrieval ready?
Does a knowledge tool make retrieval ready?
No. Inspect the document, attachment, index, and retrieval behavior separately. Start with RAG.