---
summary: "Expose an OpenResponses-compatible /v1/responses HTTP endpoint from the Gateway"
read_when:
  - Integrating clients that speak the OpenResponses API
  - You want item-based inputs, client tool calls, or SSE events
title: "OpenResponses API"
---

# 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, security, and routing

Operational behavior matches [OpenAI Chat Completions](/gateway/openai-http-api):

- use `Authorization: Bearer <token>` with the normal Gateway auth config
- treat the endpoint as full operator access for the gateway instance
- select agents with `model: "openclaw"`, `model: "openclaw/default"`, `model: "openclaw/<agentId>"`, or `x-openclaw-agent-id`
- use `x-openclaw-model` when you want to override the selected agent's backend model
- use `x-openclaw-session-key` for explicit session routing
- use `x-openclaw-message-channel` when you want a non-default synthetic ingress channel context

Enable or disable this endpoint with `gateway.http.endpoints.responses.enabled`.

The same compatibility surface also includes:

- `GET /v1/models`
- `GET /v1/models/{id}`
- `POST /v1/embeddings`
- `POST /v1/chat/completions`

For the canonical explanation of how agent-target models, `openclaw/default`, embeddings pass-through, and backend model overrides fit together, see [OpenAI Chat Completions](/gateway/openai-http-api#agent-first-model-contract) and [Model list and agent routing](/gateway/openai-http-api#model-list-and-agent-routing).

## 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`
- `truncation`

Supported:

- `previous_response_id`: OpenClaw reuses the earlier response session when the request stays within the same agent/user/requested-session scope.

## 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 “current message.”
- Earlier user/assistant messages are included as history for context.

### `function_call_output` (turn-based tools)

Send tool results back to the model:

```json
{
  "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:

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

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

## Files (`input_file`)

Supports base64 or URL sources:

```json
{
  "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`
- `maxUrlParts`: `8` (total URL-based `input_file` + `input_image` parts per request)
- Requests are guarded (DNS resolution, private IP blocking, redirect caps, timeouts).
- Optional hostname allowlists are supported per input type (`files.urlAllowlist`, `images.urlAllowlist`).
  - Exact host: `"cdn.example.com"`
  - Wildcard subdomains: `"*.assets.example.com"` (does not match apex)
  - Empty or omitted allowlists mean no hostname allowlist restriction.
- To disable URL-based fetches entirely, set `files.allowUrl: false` and/or `images.allowUrl: false`.

## File + image limits (config)

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

```json5
{
  gateway: {
    http: {
      endpoints: {
        responses: {
          enabled: true,
          maxBodyBytes: 20000000,
          maxUrlParts: 8,
          files: {
            allowUrl: true,
            urlAllowlist: ["cdn.example.com", "*.assets.example.com"],
            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,
            urlAllowlist: ["images.example.com"],
            allowedMimes: [
              "image/jpeg",
              "image/png",
              "image/gif",
              "image/webp",
              "image/heic",
              "image/heif",
            ],
            maxBytes: 10485760,
            maxRedirects: 3,
            timeoutMs: 10000,
          },
        },
      },
    },
  },
}
```

Defaults when omitted:

- `maxBodyBytes`: 20MB
- `maxUrlParts`: 8
- `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
- HEIC/HEIF `input_image` sources are accepted and normalized to JPEG before provider delivery.

Security note:

- URL allowlists are enforced before fetch and on redirect hops.
- Allowlisting a hostname does not bypass private/internal IP blocking.
- For internet-exposed gateways, apply network egress controls in addition to app-level guards.
  See [Security](/gateway/security).

## 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:

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

Common cases:

- `401` missing/invalid auth
- `400` invalid request body
- `405` wrong method

## Examples

Non-streaming:

```bash
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:

```bash
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"
  }'
```
