Node reference
MCP node: call a tool on an MCP server
mcp_tool · Updated September 21, 2026
The MCP node calls one tool on a server you connected on the MCP page, using its stored auth. The server publishes what its tools are called and what they take, so the node's inputs come from the server itself.
When to use it
- Using a service that already ships an MCP server, instead of wiring its API by hand.
- Giving an agent a whole server's worth of tools it can choose between.
Ports
- Inputs
in- Outputs
outerror- Tool
attachable to an agent's tools port
Configuration
- Server
server_idrequired - string
- Tool
toolrequired - string
- Inputs
args - objectValues may use templates. As a tool, the agent fills whatever is left empty.
- Tool description
tool_description - stringShown to the agent when this node is attached as a tool. Defaults to the tool's own description.
- Offer every tool on this server
expose_all - boolean · default falseWhen attached to an agent, let it choose any of the server's tools, not just this one.
Output
Fires out with the tool's text, its structured result when it returns one, and elapsed_ms. A tool that reports an error fails the node, which fires error under the error_port error mode.
Example
Tool: read_wiki_structure
repoName: {{ trigger.repo }}Good to know
- Inputs you fill in are fixed; as a tool, the agent only chooses the ones left empty.
- Turn on Offer every tool on this server to let an agent pick any of the server's tools.
- See MCP servers for connecting one and keeping its tools current.
Keep reading
- MCP servers: a marketplace of tools for your workflowsConnect a Model Context Protocol server from the marketplace or by URL, and call its tools from a workflow node or hand them to an agent.
- Agent node: Claude with tools and structured outputThe Agent node calls Claude with your prompt, can call attached HTTP tools in a loop, and returns text plus schema-validated structured output for branching.
- API node: call your own APIs with saved authThe API node calls an HTTP API you added under APIs, with its saved auth, through a named endpoint or a custom request. It also works as an agent tool.
Build it on the canvas
Create a free account, describe the workflow or wire it yourself, and run it in the browser.