providers

The providers block declares which model providers the agent may use and how to connect to them. The value of agent.model.provider must match one of the sub-block names declared here.

providers {
  anthropic {
    models = ["claude-haiku-4-5"]

    config {
      api_key = secret(runtime("ANTHROPIC_API_KEY"))
    }
  }
}

agent "assistant" {
  graph {
    type = "react"
  }

  model {
    provider = "anthropic"
    name     = "claude-haiku-4-5"
  }
}

Shared structure

All provider sub-blocks follow the same general shape. The details of which fields are available inside config differ per provider and are documented on each provider's reference page.

models is an optional list of model entries. When present it acts as an allowlist: only the named models may be used in agent.model.name when this provider is selected. When absent, any model name is accepted. Each entry is either a plain model name string, or a config object with a name field and an optional params block for model-specific inference parameter overrides:

models = [
  "claude-haiku-4-5",
  {
    name = "claude-sonnet-4-6"
    params {
      max_tokens  = 8192
      temperature = 0.7
    }
  }
]

config is an optional block containing connection settings such as API keys and base URLs. When omitted entirely, the provider falls back to its SDK defaults, typically by reading well-known environment variables. See each provider's page for the specific fallback behavior.

params is an optional block that sets inference parameter defaults for every model request made through this provider. These defaults are baked into every model instance at startup. Individual model entries in the models list can override specific fields by declaring their own params block; model-level values take precedence over provider-level values.

params {
  max_tokens  = 4096
  temperature = 0.5
}

runtime() may wrap any config or params value to defer its resolution to deployment time. This lets you supply keys, URLs, and parameter values via environment variables without hardcoding them in the manifest.

secret() should additionally wrap any value that is sensitive. Marking a value as secret prevents it from appearing in build artifacts and in the output of agentc inspect. API keys should always be written as secret(runtime("ENV_VAR_NAME")).

Supported providers