Langfuse MCP Server

Instructions

Implementation Reference

• src/tools/get-prompt-detail.ts:12-39 (handler)

  The async handler function that executes the tool logic: fetches prompt data from Langfuse client and returns formatted JSON or error.

  export async function getPromptDetail(
    client: LangfuseAnalyticsClient,
    args: GetPromptDetailArgs
  ) {
    try {
      const promptData = await client.getPrompt(args.promptName, args.version, args.label);
  
      return {
        content: [
          {
            type: 'text' as const,
            text: JSON.stringify(promptData, null, 2),
          },
        ],
      };
    } catch (error) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      return {
        content: [
          {
            type: 'text' as const,
            text: `Error getting prompt detail: ${errorMessage}`,
          },
        ],
        isError: true,
      };
    }
  }

• src/tools/get-prompt-detail.ts:4-8 (schema)

  Zod schema for input validation of get_prompt_detail tool arguments.

  export const getPromptDetailSchema = z.object({
    promptName: z.string().describe('The prompt name to retrieve'),
    version: z.number().optional().describe('Specific version to retrieve (if not provided, gets latest)'),
    label: z.string().optional().describe('Specific label to retrieve'),
  });

• src/index.ts:600-621 (registration)

  Tool descriptor registration in the listToolsRequestHandler, specifying name, description, and inputSchema.

  {
    name: 'get_prompt_detail',
    description: 'Get detailed information about a specific prompt template.',
    inputSchema: {
      type: 'object',
      properties: {
        promptName: {
          type: 'string',
          description: 'The prompt name to retrieve',
        },
        version: {
          type: 'number',
          description: 'Specific version to retrieve (if not provided, gets latest)',
        },
        label: {
          type: 'string',
          description: 'Specific label to retrieve',
        },
      },
      required: ['promptName'],
    },
  },

• src/index.ts:1087-1090 (registration)

  Dispatch case in the CallToolRequestHandler switch statement that validates args with schema and invokes the handler.

  case 'get_prompt_detail': {
    const args = getPromptDetailSchema.parse(request.params.arguments);
    return await getPromptDetail(this.client, args);
  }

• src/index.ts:71-71 (registration)

  Import statement bringing in the handler function and schema from the tool module.

  import { getPromptDetail, getPromptDetailSchema } from './tools/get-prompt-detail.js';