Build agent

Build Agent Skill

Turn a description like "an agent that writes commit messages" into a working, tested NanoCodana agent. NanoCodana is a coding-agent framework on the Vercel AI SDK: an agent is created with NodeAgent({ ... }) and run with agent.generate({ prompt }) or agent.stream({ messages }).

Template — a minimal runnable agent

Write a file like this to the current working directory (adapt the name, model, system prompt, and tools to the request). It reads the API key from the environment — no dotenv needed, because it inherits the parent process's env.

import { NodeAgent } from '@nanocodana/nodejs'
import { createAnthropic } from '@ai-sdk/anthropic'

const model = createAnthropic({ apiKey: process.env.ANTHROPIC_API_KEY })(
  'claude-sonnet-4-5',
)

const agent = NodeAgent({
  model,
  workingDirectory: process.cwd(),
  systemPrompt: `<one paragraph describing this agent's single job>`,
  // Optional: gate or restrict tools for safety, e.g.
  //   needsApproval: ['Write', 'Edit', 'Delete'],
})

// The task comes in as the first CLI arg (fallback for a quick smoke test).
const task = process.argv[2] ?? '<a representative default task>'
const result = await agent.generate({ prompt: task })
console.log(result.text)

If OPENAI_API_KEY is set instead of ANTHROPIC_API_KEY, use createOpenAI(...)('gpt-4o') from @ai-sdk/openai.

Steps

1. Clarify the agent's single purpose, its model, and which tools it needs. Keep the scope to one clear job.
2. Write the agent script to <name>.mjs in the current working directory.
3. (Optional) Write a skill at .agents/skills/<name>/SKILL.md if the agent needs reusable, loadable instructions — then have the generated agent load it (omit skills to let it auto-discover from its working dir).
4. Test it by running it with the host shell and a representative task:

   node <name>.mjs "a representative task for this agent"
   

   (Use Bash with host: true — running Node needs the real shell.)
5. Read the output. If the agent misbehaves, fix the script or its system prompt / skill and run it again. Don't stop until it produces a sensible result.
6. Summarize what you built: the file(s) created, the agent's purpose, and the exact command to run it.

Rules

• Keep generated agents minimal — only @nanocodana/nodejs plus one AI SDK provider. No extra dependencies.
• Default to safe tools. Do not enable host Bash or destructive tools in a generated agent unless the user explicitly asks.
• Always test before declaring done.
• Do NOT build an agent whose job is to build other agents (no recursion).