Elysia MCP Adapter — routes become protocol

Implement the exported TaskProvider interface, then pass it when installing the adapter:

import { Elysia } from 'elysia'
import { mcp, type TaskProvider } from '@mwillbanks/elysia-mcp-adapter'

const provider: TaskProvider = createDurableProvider()

const app = new Elysia()
  .use(mcp({
    allowedRoutes: [],
    extensions: {
      tasks: {
        version: 'current',
        provider,
        defaultTtl: 86_400_000,
        pollInterval: 1_000
      }
    }
  }))
  .mcpTool('reports.generate', generateReport, {
    description: 'Generate a report in a durable worker',
    taskExecution: 'required'
  })

The client must declare io.modelcontextprotocol/tasks in its request-scoped capabilities. The initial tools/call returns a working task with resultType: "task"; poll it with tasks/get or open subscriptions/listen.

Start with the tested subprocess example before adapting the provider to your database and worker platform.

Tasks quick start