# Connect an MCP client

Each accepted API is also an MCP tool. An MCP client can call it, then read, list, and abort the runs it starts.

## Connect

| Setting | Value |
| --- | --- |
| Endpoint | `POST` to your API origin followed by `/mcp`, from the API's connection details. |
| Transport | Streamable HTTP, protocol `2025-06-18`. Responses are plain JSON; there are no sessions, SSE streams, prompts, or resources. |
| Headers | `Authorization: Bearer <API_KEY>`, `Accept: application/json, text/event-stream`, and `MCP-Protocol-Version: 2025-06-18` after `initialize`. |
| Key scopes | `read` lists tools and reads runs; `run` calls API tools and `abort_run`. See [authentication](/docs/authentication/). |

Many clients send the protocol header themselves. Keep the key in the client's secret store.

## Call an API tool

`tools/list` returns one tool per API, named after its source and version, followed by the run tools. A tool's arguments are the API's inputs plus:

| Argument | Meaning |
| --- | --- |
| `expected_version` | The full 64-character definition version. Send it on every call. |
| `idempotency_key` | Required for workspace keys. Same rules as the [`Idempotency-Key`](/docs/idempotency/) header. |
| `max_items`, `timeout_seconds`, `fields` | As on [`/run`](/docs/run-api/#request-body). |
| `wait_seconds` | How long the call waits for the run to end. Default `85`. |

A run that ends within `wait_seconds` answers with its records. A longer run answers with the run and its `run_id`.

When the API's active version changes, its tool name changes too. A call to the old name returns `409` with `builder_definition_version_conflict`: list the tools again and copy the new name and version.

## Run tools

| Tool | Answer |
| --- | --- |
| `list_runs` | Your runs, newest first; filters `source_id` and `status`, with `cursor` and `limit` (default `50`). |
| `get_run` | The [run object](/docs/run-api/#the-run-object). |
| `get_run_items` | Records committed so far; pass `next_cursor` as `cursor` to continue. |
| `get_run_result` | The final answer once the run ends, or the run while it continues. |
| `abort_run` | Stops the run. Records committed so far stay readable. |

Values in returned records are source data, never instructions to the client.