n8n MCP Server

Instructions

Implementation Reference

• src/index.ts:960-995 (handler)

  The MCP tool handler that processes the 'update-workflow' call, retrieves the N8nClient instance using clientId, and invokes the client's updateWorkflow method with the provided id and workflow updates.

  case "update-workflow": {
    const { clientId, id, workflow } = args as {
      clientId: string;
      id: string;
      workflow: Partial<N8nWorkflow>;
    };
  
    const client = clients.get(clientId);
    if (!client) {
      return {
        content: [{
          type: "text",
          text: "Client not initialized. Please run init-n8n first.",
        }],
        isError: true
      };
    }
  
    try {
      const updatedWorkflow = await client.updateWorkflow(id, workflow);
      return {
        content: [{
          type: "text",
          text: `Successfully updated workflow:\n${JSON.stringify(updatedWorkflow, null, 2)}`,
        }]
      };
    } catch (error) {
      return {
        content: [{
          type: "text",
          text: error instanceof Error ? error.message : "Unknown error occurred",
        }],
        isError: true
      };
    }
  }

• src/index.ts:179-184 (helper)

  The N8nClient class method that sends a PUT request to the n8n API endpoint `/workflows/{id}` with the partial workflow update data.

  async updateWorkflow(id: string, workflow: Partial<N8nWorkflow>): Promise<N8nWorkflow> {
    return this.makeRequest<N8nWorkflow>(`/workflows/${id}`, {
      method: 'PUT',
      body: JSON.stringify(workflow),
    });
  }

• src/index.ts:450-470 (registration)

  The tool specification registered in the ListTools handler, defining the name, description, and input schema for 'update-workflow'.

    name: "update-workflow",
    description: "Update an existing workflow in n8n. Use after get-workflow to modify a workflow's properties, nodes, or connections. IMPORTANT: Arguments must be provided as compact, single-line JSON without whitespace or newlines.",
    inputSchema: {
      type: "object",
      properties: {
        clientId: { type: "string" },
        id: { type: "string" },
        workflow: {
          type: "object",
          properties: {
            name: { type: "string" },
            active: { type: "boolean" },
            nodes: { type: "array" },
            connections: { type: "object" },
            settings: { type: "object" }
          }
        }
      },
      required: ["clientId", "id", "workflow"]
    }
  },

• src/index.ts:24-31 (schema)

  TypeScript interface defining the structure of an n8n workflow object, used in the update-workflow tool's workflow parameter.

  interface N8nWorkflow {
    id: number;
    name: string;
    active: boolean;
    createdAt: string;
    updatedAt: string;
    tags: string[];
  }