Railway MCP Server

Instructions

Implementation Reference

• src/tools/variable.tool.ts:32-63 (registration)

  Full registration of the 'variable_set' tool using createTool, including description, input schema, and handler function.

  createTool(
    "variable_set",
    formatToolDescription({
      type: 'API',
      description: "Create or update an environment variable",
      bestFor: [
        "Setting configuration values",
        "Updating connection strings",
        "Managing service secrets"
      ],
      notFor: [
        "Bulk variable updates (use variable_bulk_set)",
        "Temporary configuration changes"
      ],
      relations: {
        prerequisites: ["service_list"],
        nextSteps: ["deployment_trigger", "service_restart"],
        alternatives: ["variable_bulk_set"],
        related: ["variable_list", "variable_delete"]
      }
    }),
    {
      projectId: z.string().describe("ID of the project containing the service"),
      environmentId: z.string().describe("ID of the environment for the variable (usually obtained from service_list)"),
      name: z.string().describe("Name of the environment variable"),
      value: z.string().describe("Value to set for the variable"),
      serviceId: z.string().optional().describe("Optional: ID of the service for the variable, if omitted creates/updates a shared variable")
    },
    async ({ projectId, environmentId, name, value, serviceId }) => {
      return variableService.upsertVariable(projectId, environmentId, name, value, serviceId);
    }
  ),

• src/tools/variable.tool.ts:60-62 (handler)

  Handler function that executes the tool logic by delegating to variableService.upsertVariable.

  async ({ projectId, environmentId, name, value, serviceId }) => {
    return variableService.upsertVariable(projectId, environmentId, name, value, serviceId);
  }

• src/tools/variable.tool.ts:53-59 (schema)

  Zod schema defining the input parameters for the variable_set tool.

  {
    projectId: z.string().describe("ID of the project containing the service"),
    environmentId: z.string().describe("ID of the environment for the variable (usually obtained from service_list)"),
    name: z.string().describe("Name of the environment variable"),
    value: z.string().describe("Value to set for the variable"),
    serviceId: z.string().optional().describe("Optional: ID of the service for the variable, if omitted creates/updates a shared variable")
  },

• src/tools/index.ts:32-36 (registration)

  MCP server registration loop that registers the variable_set tool (imported via variableTools).

  allTools.forEach((tool) => {
    server.tool(
      ...tool
    );
  });

• src/services/variable.service.ts:37-54 (helper)

  Supporting service method upsertVariable called by the tool handler to perform the actual variable update via client API.

  async upsertVariable(projectId: string, environmentId: string, name: string, value: string, serviceId?: string) {
    try {
      await this.client.variables.upsertVariable({
        projectId,
        environmentId,
        name,
        value,
        serviceId
      });
  
      const variableType = serviceId ? "service variable" : "shared environment variable";
      return createSuccessResponse({
        text: `Successfully set ${variableType} "${name}"`
      });
    } catch (error) {
      return createErrorResponse(`Error setting variable: ${formatError(error)}`);
    }
  }