Messages (Anthropic-compatible)

The messages endpoints provide an Anthropic Messages-compatible surface over Meta Model API. Supply requests in the Anthropic wire format — POST /v1/messages generates an assistant message and POST /v1/messages/count_tokens counts input tokens without generating. Authentication, rate limits, and billing match the other Model API endpoints; supported tools are developer-defined (custom) functions and built-in web_search.

• Create a message
• Count tokens
• Schemas

For guidance on reasoning replay, tool calling, and structured output that also applies to the shared inference pipeline, see the Responses feature page.