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Node ReferenceMCP Tool Node
Node Reference

MCP Tool Node

Define a published workflow-backed MCP tool surface.

The MCP Tool node is part of Builder Studio's MCP Server Builder: a set of node types for defining the tools a published user MCP server exposes to external clients. An MCP Tool node declares one workflow-backed tool surface — its name, the inputs it accepts, and the workflow that runs when an MCP client calls it.

Availability
The MCP Server Builder node types are part of the published user MCP roadmap and are not yet available to place on the canvas in this build. This page documents their intended purpose so you can plan around them. For what you can do today, build and call the platform MCP server with the Builder MCP CLI and publish servers through the marketplace.
Two different MCP surfaces
Builder Studio's own MCP server (canvas, execution, and workspace tools you call from Cursor, Claude Code, or Codex) is a separate, already-live surface. The MCP Server Builder nodes are about publishing your ownMCP server that wraps your workflows, not about calling Builder Studio's built-in tools.

What it is meant to define

  • A tool name and description that an external MCP client sees when it lists available tools.
  • The input surface for the tool — the arguments a caller must or may provide.
  • The workflow that runs for each call, so the published tool is backed by a canvas graph rather than hand-written handler code.

How it is intended to fit together

  1. Define the tool surface

    An MCP Tool node names the tool and declares its inputs. This is the entry point a published MCP server advertises to clients.

  2. Back it with a workflow

    The rest of the canvas graph runs when the tool is called. Inputs flow in from the tool node; the workflow does the work.

  3. Shape the response

    An MCP Output node selects which workflow value is returned to the calling client.

  4. Declare any credentials

    An MCP Credential node declares the encrypted credential surface a tool handler needs, so secrets are configured rather than embedded.

Where to continue today
Use the Marketplace overview for the supported published-MCP consumption paths, and Building for the marketplace for the current publishing model. The Builder MCP CLI section covers calling the platform MCP server.

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