Set the system prompt, greeting, and language model, and tune how the agent responds.
The Think section controls the conversation: the system prompt, the greeting,
the language model (LLM), and what the agent does when a caller goes quiet. For
how Listen, Think, and Speak fit together, see the
Execution Layer overview. For how to write
the prompt itself, see Agent behavior.
Open your project and go to the Think section. Edit the System
prompt and the Greeting the agent opens with.
The Think section with the system prompt and greeting fields.
system_prompt and greeting are top-level fields, so you can update them
on their own. Set inbound_greeting or outbound_greeting to open phone
calls with a different line.
{ "system_prompt": "You are a support agent for Wayne Enterprises.", "greeting": "Hi, how can I help you today?"}
Open your project and go to the Think section. Open the LLM model
dropdown and pick a model. As with Listen, the dropdown separates SLNG
models, hosted in your region, from BYOK, models you reach with your own
provider key.
The Think section LLM model selector.
To use the BYOK tab, register your provider key first; see
Bring your own key.
Send the whole models object. A PATCH replaces it as a unit rather than
merging fields, so change llm and keep the other model fields as they are.
Prefer a model under the slng/ prefix to run in your region. A bare
provider/model uses the provider’s model through SLNG; add your own key
(BYOK) to run it on your account. See
Choose a model route.
idle_nudges sets what the agent says when a caller stops responding. It nudges
once, nudges again, then ends the call, each after its own delay. Edit the text
and delays, or set enabled to false to keep quiet.
{ "idle_nudges": { "enabled": true, "first_nudge_delay_seconds": 15, "first_nudge_text": "Are you still there?", "hangup_delay_seconds": 15 }}
The Context Router sits in front of the language model and decides how to handle
each turn, so some turns skip the large model entirely. Toggle it with
llm_router_enabled. For how routing works, see
Context Router.
Tools and MCP servers are attached separately, not set in this section, and
tool_refs and mcp_refs cannot be changed with PATCH. See
Give an agent a tool.
The LLM step can fall back to another model and has its own per-turn timeout
(models.fallbacks.llm, models.llm_first_token_timeout_s). These work the same
way across all three sections. See
Reliability.
