Google ADK (Agent Development Kit)

Setup

Install the Braintrust and @google/adk packages, then set your API keys. Auto-instrumentation supports @google/adk v0.6.1 to v0.6.x and v1.0.0 to v1.x. Versions v0.7.0 through v0.9.x aren’t supported.

Install packages

pnpm add braintrust @google/adk

npm install braintrust @google/adk

Set environment variables

.env

BRAINTRUST_API_KEY=<your-braintrust-api-key>
GEMINI_API_KEY=<your-gemini-api-key>

# For organizations on the EU data plane, use https://api-eu.braintrust.dev
# For self-hosted deployments, use your data plane URL
# BRAINTRUST_API_URL=<your-braintrust-api-url>

Auto-instrumentation

To trace ADK agents without modifying your application code, initialize Braintrust normally, then run your app with Braintrust’s import hook to patch the ADK SDK at runtime.

Initialize Braintrust and call ADK

import { initLogger } from "braintrust";
import * as adk from "@google/adk";

initLogger({
  projectName: "my-adk-project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const { LlmAgent, InMemoryRunner, FunctionTool } = adk;

// Create the tools
const getWeatherTool = new FunctionTool({
  name: "get_weather",
  description: "Get weather for a city.",
  parameters: {
    type: "object",
    properties: {
      city: {
        type: "string",
        description: "The city to look up weather for",
      },
    },
    required: ["city"],
  },
  execute: ({ city }) => {
    return { temperature: 72, condition: "sunny", city };
  },
});

const getCurrentTimeTool = new FunctionTool({
  name: "get_current_time",
  description: "Get the current time.",
  parameters: {
    type: "object",
    properties: {},
  },
  execute: () => {
    return new Date().toLocaleTimeString("en-US", {
      hour: "numeric",
      minute: "2-digit",
      hour12: true,
    });
  },
});

// Create the agent
const agent = new LlmAgent({
  name: "weather_time_assistant",
  model: "gemini-2.5-flash",
  instruction: "You are a helpful assistant that can check weather and time.",
  tools: [getWeatherTool, getCurrentTimeTool],
});

// Create the runner and a session
const runner = new InMemoryRunner({ agent, appName: "weather_app" });
const userId = "user123";
const sessionId = "session123";
await runner.sessionService.createSession({
  appName: runner.appName,
  userId,
  sessionId,
});

// Run the agent
for await (const event of runner.runAsync({
  userId,
  sessionId,
  newMessage: {
    role: "user",
    parts: [{ text: "What's the weather like in New York?" }],
  },
})) {
  console.log(event);
}

Run with the import hook

node --import braintrust/hook.mjs trace-adk-auto.js

The auto-instrumentation example uses plain JavaScript so node --import can run the file directly. The Braintrust APIs work the same in TypeScript projects — compile your TypeScript to JavaScript, then run the compiled file with the import hook.

If you’re using a bundler, see Trace LLM calls for plugin and loader setup.

Manual instrumentation

To trace the ADK module manually, wrap it yourself with wrapGoogleADK() and destructure the wrapped classes from the result.

Manual instrumentation traces runner, agent, and tool spans, but not LLM call spans. ADK constructs its model client internally, so user-side wrapping cannot intercept the underlying model calls. To capture LLM spans, use auto-instrumentation instead.

import { initLogger, wrapGoogleADK } from "braintrust";
import * as adk from "@google/adk";

initLogger({
  projectName: "my-adk-project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const { LlmAgent, InMemoryRunner, FunctionTool } = wrapGoogleADK(adk);

// Create the tools
const getWeatherTool = new FunctionTool({
  name: "get_weather",
  description: "Get weather for a city.",
  parameters: {
    type: "object",
    properties: {
      city: {
        type: "string",
        description: "The city to look up weather for",
      },
    },
    required: ["city"],
  },
  execute: ({ city }) => {
    return { temperature: 72, condition: "sunny", city };
  },
});

const getCurrentTimeTool = new FunctionTool({
  name: "get_current_time",
  description: "Get the current time.",
  parameters: {
    type: "object",
    properties: {},
  },
  execute: () => {
    return new Date().toLocaleTimeString("en-US", {
      hour: "numeric",
      minute: "2-digit",
      hour12: true,
    });
  },
});

// Create the agent
const agent = new LlmAgent({
  name: "weather_time_assistant",
  model: "gemini-2.5-flash",
  instruction: "You are a helpful assistant that can check weather and time.",
  tools: [getWeatherTool, getCurrentTimeTool],
});

// Create the runner and a session
const runner = new InMemoryRunner({ agent, appName: "weather_app" });
const userId = "user123";
const sessionId = "session123";
await runner.sessionService.createSession({
  appName: runner.appName,
  userId,
  sessionId,
});

// Run the agent
for await (const event of runner.runAsync({
  userId,
  sessionId,
  newMessage: {
    role: "user",
    parts: [{ text: "What's the weather like in New York?" }],
  },
})) {
  console.log(event);
}

What Braintrust traces

Braintrust captures:

Runner execution as a task span, with the new message as input, the final event as output, and the user and session IDs in metadata
Agent invocations as task spans nested under the runner, with the agent name and model in metadata
Tool calls as tool spans nested under the agent, with arguments as input, the result as output, and the tool name plus call ID in metadata
Token usage (prompt, completion, total, cached, and reasoning tokens) aggregated across the run on the runner span
LLM calls inside ADK as nested LLM spans, traced via Braintrust’s Google GenAI integration since ADK uses Google GenAI internally for model calls

AI providers

SDKs

Developer tools

Google ADK (Agent Development Kit)

Setup

Auto-instrumentation

Manual instrumentation

What Braintrust traces

Resources

​Setup

​Auto-instrumentation

​Manual instrumentation

​What Braintrust traces

​Resources

Setup

Auto-instrumentation

Manual instrumentation

What Braintrust traces

Resources