OpenResponses API (HTTP)

OpenClaw’s Gateway can serve an OpenResponses-compatible POST /v1/responses endpoint.

This endpoint is disabled by default. Enable it in config first.

  • POST /v1/responses
  • Same port as the Gateway (WS + HTTP multiplex): http://<gateway-host>:<port>/v1/responses

Under the hood, requests are executed as a normal Gateway agent run (same codepath as openclaw agent), so routing/permissions/config match your Gateway.

Authentication

Uses the Gateway auth configuration. Send a bearer token:

  • Authorization: Bearer <token>

Notes:

  • When gateway.auth.mode="token", use gateway.auth.token (or OPENCLAW_GATEWAY_TOKEN).
  • When gateway.auth.mode="password", use gateway.auth.password (or OPENCLAW_GATEWAY_PASSWORD).

Choosing an agent

No custom headers required: encode the agent id in the OpenResponses model field:

  • model: "openclaw:<agentId>" (example: "openclaw:main", "openclaw:beta")
  • model: "agent:<agentId>" (alias)

Or target a specific OpenClaw agent by header:

  • x-openclaw-agent-id: <agentId> (default: main)

Advanced:

  • x-openclaw-session-key: <sessionKey> to fully control session routing.

Enabling the endpoint

Set gateway.http.endpoints.responses.enabled to true:

{
  gateway: {
    http: {
      endpoints: {
        responses: { enabled: true }
      }
    }
  }
}

Disabling the endpoint

Set gateway.http.endpoints.responses.enabled to false:

{
  gateway: {
    http: {
      endpoints: {
        responses: { enabled: false }
      }
    }
  }
}

Session behavior

By default the endpoint is stateless per request (a new session key is generated each call).

If the request includes an OpenResponses user string, the Gateway derives a stable session key from it, so repeated calls can share an agent session.

Request shape (supported)

The request follows the OpenResponses API with item-based input. Current support:

  • input: string or array of item objects.
  • instructions: merged into the system prompt.
  • tools: client tool definitions (function tools).
  • tool_choice: filter or require client tools.
  • stream: enables SSE streaming.
  • max_output_tokens: best-effort output limit (provider dependent).
  • user: stable session routing.

Accepted but currently ignored:

  • max_tool_calls
  • reasoning
  • metadata
  • store
  • previous_response_id
  • truncation

Items (input)

message

Roles: system, developer, user, assistant.

  • system and developer are appended to the system prompt.
  • The most recent user or function_call_output item becomes the β€œcurrent message.”
  • Earlier user/assistant messages are included as history for context.

function_call_output (turn-based tools)

Send tool results back to the model:

{
  "type": "function_call_output",
  "call_id": "call_123",
  "output": "{\"temperature\": \"72F\"}"
}

reasoning and item_reference

Accepted for schema compatibility but ignored when building the prompt.

Tools (client-side function tools)

Provide tools with tools: [{ type: "function", function: { name, description?, parameters? } }].

If the agent decides to call a tool, the response returns a function_call output item. You then send a follow-up request with function_call_output to continue the turn.

Images (input_image)

Supports base64 or URL sources:

{
  "type": "input_image",
  "source": { "type": "url", "url": "https://example.com/image.png" }
}

Allowed MIME types (current): image/jpeg, image/png, image/gif, image/webp. Max size (current): 10MB.

Files (input_file)

Supports base64 or URL sources:

{
  "type": "input_file",
  "source": {
    "type": "base64",
    "media_type": "text/plain",
    "data": "SGVsbG8gV29ybGQh",
    "filename": "hello.txt"
  }
}

Allowed MIME types (current): text/plain, text/markdown, text/html, text/csv, application/json, application/pdf.

Max size (current): 5MB.

Current behavior:

  • File content is decoded and added to the system prompt, not the user message, so it stays ephemeral (not persisted in session history).
  • PDFs are parsed for text. If little text is found, the first pages are rasterized into images and passed to the model.

PDF parsing uses the Node-friendly pdfjs-dist legacy build (no worker). The modern PDF.js build expects browser workers/DOM globals, so it is not used in the Gateway.

URL fetch defaults:

  • files.allowUrl: true
  • images.allowUrl: true
  • Requests are guarded (DNS resolution, private IP blocking, redirect caps, timeouts).

File + image limits (config)

Defaults can be tuned under gateway.http.endpoints.responses:

{
  gateway: {
    http: {
      endpoints: {
        responses: {
          enabled: true,
          maxBodyBytes: 20000000,
          files: {
            allowUrl: true,
            allowedMimes: ["text/plain", "text/markdown", "text/html", "text/csv", "application/json", "application/pdf"],
            maxBytes: 5242880,
            maxChars: 200000,
            maxRedirects: 3,
            timeoutMs: 10000,
            pdf: {
              maxPages: 4,
              maxPixels: 4000000,
              minTextChars: 200
            }
          },
          images: {
            allowUrl: true,
            allowedMimes: ["image/jpeg", "image/png", "image/gif", "image/webp"],
            maxBytes: 10485760,
            maxRedirects: 3,
            timeoutMs: 10000
          }
        }
      }
    }
  }
}

Defaults when omitted:

  • maxBodyBytes: 20MB
  • files.maxBytes: 5MB
  • files.maxChars: 200k
  • files.maxRedirects: 3
  • files.timeoutMs: 10s
  • files.pdf.maxPages: 4
  • files.pdf.maxPixels: 4,000,000
  • files.pdf.minTextChars: 200
  • images.maxBytes: 10MB
  • images.maxRedirects: 3
  • images.timeoutMs: 10s

Streaming (SSE)

Set stream: true to receive Server-Sent Events (SSE):

  • Content-Type: text/event-stream
  • Each event line is event: <type> and data: <json>
  • Stream ends with data: [DONE]

Event types currently emitted:

  • response.created
  • response.in_progress
  • response.output_item.added
  • response.content_part.added
  • response.output_text.delta
  • response.output_text.done
  • response.content_part.done
  • response.output_item.done
  • response.completed
  • response.failed (on error)

Usage

usage is populated when the underlying provider reports token counts.

Errors

Errors use a JSON object like:

{ "error": { "message": "...", "type": "invalid_request_error" } }

Common cases:

  • 401 missing/invalid auth
  • 400 invalid request body
  • 405 wrong method

Examples

Non-streaming:

curl -sS http://127.0.0.1:18789/v1/responses \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -H 'x-openclaw-agent-id: main' \
  -d '{
    "model": "openclaw",
    "input": "hi"
  }'

Streaming:

curl -N http://127.0.0.1:18789/v1/responses \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -H 'x-openclaw-agent-id: main' \
  -d '{
    "model": "openclaw",
    "stream": true,
    "input": "hi"
  }'
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