Models

The five model providers ResponseCX routes to, the default model per provider, and how to pick per agent.

Models

ResponseCX is provider-agnostic: every agent carries a model field, and the platform routes the request to the matching provider. Leave it unset and the provider’s default applies.

Providers and defaults

Provider	Default model	Character
Anthropic	claude-sonnet-4-5-20250929	The default choice for customer-facing agents — strong instruction-following under long policies
OpenAI	gpt-4o	General-purpose; also the family behind realtime voice
Google	gemini-2.0-flash	Fast and inexpensive for high-volume, low-stakes turns
Groq (Llama)	llama-3.1-8b-instant	Lowest latency; good for classification and routing steps
xAI	grok-4-latest	Alternative frontier model

Setting the model on an agent

curl -X PUT https://api.stateset.com/v1/agents/{id} \
  -H "Authorization: Bearer $STATESET_API_KEY" \
  -H 'content-type: application/json' \
  -d '{ "model": "claude-sonnet-4-5-20250929" }'

Any model identifier the provider accepts is passed through, so a newer model is available the day the provider ships it — no platform release needed.

Match the model to the step, not the agent fleet. A common shape: a fast, cheap model (llama-3.1-8b-instant or gemini-2.0-flash) for intent classification, and a stronger model for the customer-facing reply. The classification step runs on every message; the strong model only on the ones that need it.

What the model does not decide

Model choice affects fluency, latency, and cost. It does not decide what the agent is allowed to do — that is Settings, Rules, and, for consequential actions, the decision gate.

Upgrading a model is a behaviour change. A stronger model follows your policies differently — often better, occasionally in a new wrong way. Run your evaluations against the new model before switching production traffic.

Related

• Agents — where model lives
• Settings — the constraints that bound any model
• Voice — realtime voice models are configured separately, per voice agent