MCP servers in Postman Flows

Actions in Postman Flows can function as Model Context Protocol (MCP) servers with tools defined by a special scenario. When deployed to a public URL, the action can process incoming requests and send the results as responses.

This document describes the concepts behind MCP servers in Flows. For the steps to create one, see Create an MCP server with Postman Flows.

Actions are special flows that can be deployed to a public URL in the Postman cloud. Users can send requests to the action's URL. The URL can also be triggered by external systems like webhooks, third-party apps, and other APIs. The action processes incoming data using the blocks on its canvas, then sends the result as a response.

To function as an MCP server, an action needs a scenario named toolDefinition that defines the server's MCP tools and required data. Scenarios in flows are sets of static values used by the flow's blocks. Data required by an MCP tool is referred to as an argument. The body of the toolDefinition scenario must follow the MCP tool definition structure.

Test your MCP server in Postman

You can use your MCP server from any client that supports the Model Context Protocol, such as Claude or VS Code GitHub Copilot. But you can also quickly test your MCP server from Postman, using an MCP request.

When you create an MCP request in Postman and connect to the MCP server, the request shows the available tools. You can click a tool to see its required arguments.