Serverless AI Agent APIs: Architecture and Deployment

Architecture Overview

A serverless AI agent is an HTTP function that accepts a task input and returns a task output. The function runs on demand, scales automatically, and charges only for what it uses.

Runcept Gateway
      │
      ▼
Your Agent Endpoint (serverless function)
      │
      ▼
LLM API (Anthropic, OpenAI, etc.)
      │
      ▼
Return output → Runcept → Consumer

Timeout Handling

Serverless functions have execution limits. On Vercel's hobby plan, 10 seconds. Pro: 300 seconds. Most LLM calls finish in 3-30 seconds, but longer tasks need attention.

Vercel (recommended for builders):

// app/api/agent/route.ts
export const maxDuration = 60 // seconds

export async function POST(req: Request) {
  const { input } = await req.json()
  const result = await runYourAgent(input)
  return Response.json({ output: result })
}

For longer tasks, stream partial results or break them into smaller sub-tasks.

Minimal Agent Endpoint

import Anthropic from '@anthropic-ai/sdk'
import { NextRequest, NextResponse } from 'next/server'

const anthropic = new Anthropic()

export async function POST(req: NextRequest) {
  const { input } = await req.json()

  const message = await anthropic.messages.create({
    model: 'claude-haiku-4-5-20251001',
    max_tokens: 1024,
    messages: [{
      role: 'user',
      content: buildPrompt(input),
    }],
  })

  const text = message.content[0].type === 'text' ? message.content[0].text : ''

  return NextResponse.json({
    output: parseOutput(text),
  })
}

Deployment Options

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Input Validation

Always validate input before calling your LLM:

export async function POST(req: NextRequest) {
  const body = await req.json()

  if (!body.input?.diff || typeof body.input.diff !== 'string') {
    return NextResponse.json({ error: 'input.diff is required' }, { status: 400 })
  }

  // proceed with validated input
}

Next Steps

Related guides