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MCP node

MCP node card

The MCP node calls a tool on a Model Context Protocol (MCP) server. MCP is the standard way to expose external tools — databases, search, internal APIs — to AI agents.

How it fits together

  1. You configure one or more MCP servers in the MCP_SERVERS environment variable (see MCP servers).
  2. The MCP node references a server by id and a tool by name.
  3. At run time, Sobmit connects to that server and invokes the tool with the arguments you provide.

Configuration

  • Server — the id of the configured MCP server.
  • Tool — the tool name on that server.
  • Arguments — a JSON object passed to the tool, or { "$from": "path" } to pull arguments from the run context.
  • Timeout — tool-call timeout in milliseconds.

Argument templates

Arguments support two forms:

{ "query": "hello" }

Or pull a value from the incoming payload:

{ "$from": "payload" }

Nested {path} templates inside argument strings are resolved recursively against the run context.

Example

An MCP server github exposes a tool list_issues. The MCP node:

Server: github
Tool: list_issues
Arguments: { "repo": "org/repo", "state": "open" }

Security

  • Server details (URL, headers) never enter the graph model — the node only stores the server id and tool name.
  • Header values can reference environment variables (e.g. Bearer ${TOKEN}) so secrets stay out of the flow.

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