AI SDK DevTools

Why Use DevTools

DevTools captures all AI SDK calls (generateText, streamText, ToolLoopAgent) to a local JSON file. This lets you inspect LLM requests, responses, tool calls, and multi-step interactions without manually logging.

Setup

Requires AI SDK 6. Install @ai-sdk/devtools using your project's package manager.

Wrap your model with the middleware:

import { wrapLanguageModel, gateway } from 'ai';
import { devToolsMiddleware } from '@ai-sdk/devtools';

const model = wrapLanguageModel({
  model: gateway('anthropic/claude-sonnet-4.5'),
  middleware: devToolsMiddleware(),
});

Viewing Captured Data

All runs and steps are saved to:

.devtools/generations.json

Read this file directly to inspect captured data:

cat .devtools/generations.json | jq

Or launch the web UI:

npx @ai-sdk/devtools
# Open http://localhost:4983

Data Structure

• Run: A complete multi-step interaction grouped by initial prompt
• Step: A single LLM call within a run (includes input, output, tool calls, token usage)