Write to MCP tool
Invoke an integration's MCP tool once per record.
Invoke an integration's MCP tool once per record.
When to use it
Call a connected service tool once per input record. Read the tool’s actual effect: it can write or act externally. Duplicate prevention depends on the service honouring the supplied key; inspect uncertain outcomes before repeating calls.
Add and configure
- Add Write to MCP tool from the workflow step picker.
- Give the step a recognisable name and connect its required inputs.
- Set the options below. Nested names identify fields within an object or a list item.
- Validate the recipe, inspect the test result, then run it on the intended data.
The step identifier used in the editor’s code view is write_to_mcp.
Settings
| Setting | Accepted value | Required | Default | What it controls |
|---|---|---|---|---|
Concurrency (concurrency) | integer; minimum 1; maximum 32 | No | 4 | Max in-flight MCP calls per step execution. Set to 1 for strict serial ordering (matches prior behavior). |
Idempotency Key Template (idempotency_key_template) | string or null | No | null | When set, each tool call carries an Idempotency-Key header rendered from this template (variables: ${tenant_id}, ${run_id}, ${step_id}, ${record_seq}). The MCP gateway is expected to honor the header for idempotent dispatch; absent gateway support the key is logged and still emitted so audit trails align. |
Integration Id (integration_id) | string; format uuid | Yes | Not specified | MCP integration UUID. |
Payload Path (payload_path) | string or null | No | null | Optional JSONPath — when set, the tool is called with the value at this path instead of the whole record. |
Tool Name (tool_name) | string | Yes | Not specified | Name of the tool to invoke. |
Inputs and outputs
| Direction | Port | Content | Required | Multiple records |
|---|---|---|---|---|
| Inputs | in | records | Yes | Yes |
| Outputs | out | records | Yes | Yes |
Effects, testing, and recovery
Can write or act on an external destination.
The declared preview behaviour is to skip this step. Configuration can affect preview behaviour; HTTP GET is a notable exception. Read dry runs before using a preview with live connections.
Duplicate prevention uses the configured or operation-bound key; an external receiver must recognise it. Do not assume that manually repeating the step is free of repeated effects.
Example: Post each record's message through a chat integration
Step settings:
{
"idempotency_key_template": "${run_id}:${record_seq}",
"integration_id": "88888888-8888-4888-8888-888888888888",
"payload_path": "$.message",
"tool_name": "send_message"
}
Example: Serial calls with the whole record as the tool arguments
Step settings:
{
"concurrency": 1,
"integration_id": "88888888-8888-4888-8888-888888888888",
"tool_name": "create_ticket"
}
Check the result
Inspect the selected run’s status, counts, errors, and output records. An empty collection can be a valid result, and a completed step can contain per-record failures where the step defines that behaviour. Check the next step’s expected record shape before publishing or delivering the result.