n8n MCP Server

Instructions

Implementation Reference

• src/index.ts:627-638 (registration)

  Registration of the 'create-variable' tool in the listTools response, including name, description, and input schema.

    name: "create-variable",
    description: "Create a new variable in n8n. NOTE: Requires n8n Enterprise license with variable management features enabled. Variables can be used across workflows to store and share data. IMPORTANT: Arguments must be provided as compact, single-line JSON without whitespace or newlines.",
    inputSchema: {
      type: "object",
      properties: {
        clientId: { type: "string" },
        key: { type: "string" },
        value: { type: "string" }
      },
      required: ["clientId", "key", "value"]
    }
  },

• src/index.ts:627-638 (schema)

  Input schema definition for the 'create-variable' tool.

    name: "create-variable",
    description: "Create a new variable in n8n. NOTE: Requires n8n Enterprise license with variable management features enabled. Variables can be used across workflows to store and share data. IMPORTANT: Arguments must be provided as compact, single-line JSON without whitespace or newlines.",
    inputSchema: {
      type: "object",
      properties: {
        clientId: { type: "string" },
        key: { type: "string" },
        value: { type: "string" }
      },
      required: ["clientId", "key", "value"]
    }
  },

• src/index.ts:1425-1455 (handler)

  Main handler for executing the 'create-variable' tool: validates clientId, retrieves N8nClient instance, calls createVariable method, handles success/error responses.

  case "create-variable": {
    const { clientId, key, value } = args as { clientId: string; key: string; value: string };
    const client = clients.get(clientId);
    if (!client) {
      return {
        content: [{
          type: "text",
          text: "Client not initialized. Please run init-n8n first.",
        }],
        isError: true
      };
    }
  
    try {
      await client.createVariable(key, value);
      return {
        content: [{
          type: "text",
          text: `Successfully created variable with key: ${key}`,
        }]
      };
    } catch (error) {
      return {
        content: [{
          type: "text",
          text: error instanceof Error ? error.message : "Unknown error occurred",
        }],
        isError: true
      };
    }
  }

• src/index.ts:256-261 (helper)

  N8nClient helper method that performs the actual API POST request to create a variable in n8n.

  async createVariable(key: string, value: string): Promise<void> {
    return this.makeRequest<void>('/variables', {
      method: 'POST',
      body: JSON.stringify({ key, value }),
    });
  }

• src/index.ts:49-54 (helper)

  Type definition for N8nVariable used in variable management.

  interface N8nVariable {
    id: string;
    key: string;
    value: string;
    type?: string;
  }