Langfuse MCP Server

Instructions

Input Schema

Input Schema (JSON Schema)

Implementation Reference

• src/tools/get-daily-metrics.ts:12-129 (handler)

  The main handler function that fetches daily metrics from Langfuse client, processes and filters data by date range, calculates aggregates like total tokens, costs, averages, fills missing days if requested, and returns formatted JSON response.
  export async function getDailyMetrics( client: LangfuseAnalyticsClient, args: z.infer<typeof getDailyMetricsSchema> ) { try { // Use the working getDailyMetrics API directly (same approach as cost_analysis) const dailyResponse = await client.getDailyMetrics({ tags: args.environment ? [`environment:${args.environment}`] : undefined, }); const dailyData: any[] = []; if (dailyResponse.data && Array.isArray(dailyResponse.data)) { // Filter by date range const fromDate = new Date(args.from); const toDate = new Date(args.to); const filteredData = dailyResponse.data.filter((day: any) => { const dayDate = new Date(day.date); return dayDate >= fromDate && dayDate <= toDate; }); // Process each day's data filteredData.forEach((day: any) => { // Calculate total tokens from usage breakdown let totalTokens = 0; let totalObservations = 0; if (day.usage && Array.isArray(day.usage)) { totalTokens = day.usage.reduce((sum: number, usage: any) => { return sum + (usage.totalUsage || usage.inputUsage + usage.outputUsage || 0); }, 0); totalObservations = day.usage.reduce((sum: number, usage: any) => { return sum + (usage.countObservations || 0); }, 0); } dailyData.push({ date: day.date, totalCost: day.totalCost || 0, totalTokens: totalTokens, totalTraces: day.countTraces || 0, totalObservations: totalObservations || day.countObservations || 0, avgCostPerTrace: (day.countTraces || 0) > 0 ? Math.round(((day.totalCost || 0) / (day.countTraces || 0)) * 10000) / 10000 : 0, avgTokensPerTrace: (day.countTraces || 0) > 0 ? Math.round((totalTokens / (day.countTraces || 0)) * 100) / 100 : 0, }); }); // Fill in missing days if requested if (args.fillMissingDays) { const startDate = new Date(args.from); const endDate = new Date(args.to); const dataMap = new Map(dailyData.map(d => [d.date, d])); dailyData.length = 0; // Clear array for (let date = new Date(startDate); date <= endDate; date.setDate(date.getDate() + 1)) { const dateStr = date.toISOString().split('T')[0]; const existingData = dataMap.get(dateStr); if (existingData) { dailyData.push(existingData); } else { // Fill missing day with zeros dailyData.push({ date: dateStr, totalCost: 0, totalTokens: 0, totalTraces: 0, totalObservations: 0, avgCostPerTrace: 0, avgTokensPerTrace: 0, }); } } } // Sort by date dailyData.sort((a, b) => a.date.localeCompare(b.date)); } // Return the successful result const result: DailyMetrics = { projectId: client.getProjectId(), from: args.from, to: args.to, dailyData, }; return { content: [ { type: 'text' as const, text: JSON.stringify(result, null, 2), }, ], }; } catch (error) { return { content: [ { type: 'text' as const, text: JSON.stringify({ error: 'Failed to get daily metrics', message: error instanceof Error ? error.message : 'Unknown error', projectId: client.getProjectId(), from: args.from, to: args.to, }, null, 2), }, ], isError: true, }; } }
• src/tools/get-daily-metrics.ts:5-10 (schema)

  Zod schema defining input parameters: from/to datetimes (required), optional environment filter, and fillMissingDays boolean (default true).
  export const getDailyMetricsSchema = z.object({ from: z.string().datetime(), to: z.string().datetime(), environment: z.string().optional(), fillMissingDays: z.boolean().default(true), });
• src/index.ts:1056-1059 (registration)

  Registration in the CallToolRequestSchema handler switch statement: parses arguments with schema and calls the getDailyMetrics handler function.
  case 'get_daily_metrics': { const args = getDailyMetricsSchema.parse(request.params.arguments); return await getDailyMetrics(this.client, args); }
• src/index.ts:497-524 (registration)

  Tool registration in ListToolsRequestSchema handler: defines name, description, and inputSchema for discovery.
  { name: 'get_daily_metrics', description: 'Daily usage trends and patterns.', inputSchema: { type: 'object', properties: { from: { type: 'string', format: 'date-time', description: 'Start timestamp (ISO 8601)', }, to: { type: 'string', format: 'date-time', description: 'End timestamp (ISO 8601)', }, environment: { type: 'string', description: 'Optional environment filter', }, fillMissingDays: { type: 'boolean', description: 'Fill missing days with zero values (default: true)', }, }, required: ['from', 'to'], }, },
• src/index.ts:63-63 (registration)

  Import of the handler function and schema from the tools module.
  import { getDailyMetrics, getDailyMetricsSchema } from './tools/get-daily-metrics.js';