TfL Journey Status MCP Server

Instructions

Implementation Reference

• tools/tfl/status-detail.js:9-41 (handler)

  Handler function that executes the tool logic: fetches detailed status from TfL API for the specified line ID.

  const executeFunction = async ({ lineId, app_key }) => {
    if (!lineId) {
      throw new Error('lineId is required');
    }
  
    const params = new URLSearchParams([['detail', 'true']]);
    if (app_key) {
      params.append('app_key', app_key);
    }
  
    const url = `https://api.tfl.gov.uk/Line/${encodeURIComponent(lineId)}/Status?${params.toString()}`;
    
    try {
      const response = await fetch(url, {
        method: 'GET',
        headers: {
          'Content-Type': 'application/json'
        }
      });
  
      if (!response.ok) {
        const errorData = await response.json();
        throw new Error(JSON.stringify(errorData));
      }
  
      return await response.json();
    } catch (error) {
      console.error('Error fetching status and details:', error);
      return {
        error: `An error occurred while fetching status and details: ${error instanceof Error ? error.message : JSON.stringify(error)}`
      };
    }
  };

• tools/tfl/status-detail.js:47-70 (schema)

  Tool definition object `apiTool` containing the schema (name, description, parameters) and reference to handler function.

  const apiTool = {
    function: executeFunction,
    definition: {
      type: 'function',
      function: {
        name: 'get_line_status_detail',
        description: 'Get the status and details of a TfL line.',
        parameters: {
          type: 'object',
          properties: {
            lineId: {
              type: 'string',
              description: 'The identifier of the line to query (e.g., victoria, central).'
            },
            app_key: {
              type: 'string',
              description: 'Optional application key for authentication.'
            }
          },
          required: ['lineId']
        }
      }
    }
  };

• tools/paths.js:1-5 (registration)

  toolPaths array registers the paths to tool files, including status-detail.js, used by discoverTools.

  export const toolPaths = [
    'tfl/status.js',
    'tfl/status-detail.js',
    'tfl/journey-planner.js'
  ];

• lib/tools.js:7-30 (registration)

  discoverTools function loads apiTool from each path (including status-detail.js) and returns array of tools for MCP server registration.

  export async function discoverTools() {
    const tools = await Promise.all(
      toolPaths.map(async (file) => {
        const { apiTool } = await import(`../tools/${file}`);
        return { ...apiTool, path: file };
      })
    );
  
    // deduplicate tool names
    const nameCounts = {};
  
    return tools.map((tool) => {
      const name = tool.definition?.function?.name;
      if (!name) return tool;
  
      nameCounts[name] = (nameCounts[name] || 0) + 1;
  
      if (nameCounts[name] > 1) {
        tool.definition.function.name = `${name}_${nameCounts[name]}`;
      }
  
      return tool;
    });
  }