---
title: "Send Message Streaming"
method: POST
path: "/v1/agents/{agent_id}/messages/stream"
tags: ["agents"]
---

# Send Message Streaming

`POST /v1/agents/{agent_id}/messages/stream`

Process a user message and return the agent's response.
This endpoint accepts a message from a user and processes it through the agent.
It will stream the steps of the response always, and stream the tokens if 'stream_tokens' is set to True.

## Path parameters

- `agent_id` string, required

## Request body

- LettaStreamingRequest
  - `messages` union[], required — The messages to be sent to the agent.
    - union
      - MessageCreate — Request to create a message
        - `type` 'message', nullable — The message type to be created.
        - `role` 'user' | 'system' | 'assistant', required — The role of the participant.
        - `content` union, required — The content of the message.
          - LettaMessageContentUnion[]
            - union
              - …
          - string
        - `name` string, nullable — The name of the participant.
        - `otid` string, nullable — The offline threading id associated with this message
        - `sender_id` string, nullable — The id of the sender of the message, can be an identity id or agent id
        - `batch_item_id` string, nullable — The id of the LLMBatchItem that this message is associated with
        - `group_id` string, nullable — The multi-agent group that the message was sent in
      - ApprovalCreate — Input to approve or deny a tool call request
        - `type` 'approval' — The message type to be created.
        - `approve` boolean, required — Whether the tool has been approved
        - `approval_request_id` string, required — The message ID of the approval request
        - `reason` string, nullable — An optional explanation for the provided approval status
  - `max_steps` integer — Maximum number of steps the agent should take to process the request.
  - `use_assistant_message` boolean — Whether the server should parse specific tool call arguments (default `send_message`) as `AssistantMessage` objects.
  - `assistant_message_tool_name` string — The name of the designated message tool.
  - `assistant_message_tool_kwarg` string — The name of the message argument in the designated message tool.
  - `include_return_message_types` MessageType[], nullable — Only return specified message types in the response. If `None` (default) returns all messages.
  - `enable_thinking` string — If set to True, enables reasoning before responses or tool calls from the agent.
  - `stream_tokens` boolean — Flag to determine if individual tokens should be streamed, rather than streaming per step.
  - `include_pings` boolean — Whether to include periodic keepalive ping messages in the stream to prevent connection timeouts.
  - `background` boolean — Whether to process the request in the background.

## Response `200`

Successful response

- unknown

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.net/yu-code666/apis/letta-api.md) · [All operations](https://skmtc.net/yu-code666/apis/letta-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/yu-code666/letta-api/versions/6cec99480c13/schema)