Draft Text from a Tool

import { toolDefinition } from '@tanstack/ai'
import { createMCPServer } from '@tanstack/ai-mcp/server'
import type { MCPToolContext } from '@tanstack/ai-mcp/server'
import { z } from 'zod'

const draftNote = toolDefinition({
  name: 'draft_note',
  description: 'Draft a short note about a topic',
  inputSchema: z.object({
    topic: z.string(),
  }),
}).server<MCPToolContext>(async (args, ctx) => {
  const draft = await ctx.context.sample({
    messages: [
      {
        role: 'user',
        content: `Write a short note about ${args.topic}.`,
      },
    ],
  })

  if (typeof draft !== 'string') {
    throw new Error('The sample result is not text.')
  }

  return draft
})

const server = createMCPServer({
  name: 'notes',
  version: '1.0.0',
  tools: [draftNote],
  sample: async (request) => {
    const first = request.messages[0]
    const content = first === undefined ? '' : first.content
    return `Draft: ${content}`
  },
})

export function handleMcp(request: Request) {
  return server.fetch(request)
}