OpenRouter Agent

@openrouter/agent is OpenRouter’s TypeScript agent toolkit for agent loops.

TypeScript

Setup

Install packages

# pnpm
pnpm add braintrust @openrouter/agent
# npm
npm install braintrust @openrouter/agent

Set environment variables

.env

OPENROUTER_API_KEY=<your-openrouter-api-key>
BRAINTRUST_API_KEY=<your-braintrust-api-key>

# If you are self-hosting Braintrust, set the URL of your hosted dataplane
# BRAINTRUST_API_URL=<your-braintrust-api-url>

Braintrust supports @openrouter/agent v0.1.2 and later.

Auto-instrumentation

Braintrust can auto-instrument OpenRouter.callModel() calls. This is the recommended setup for most projects.

import { initLogger } from "braintrust";
import { OpenRouter } from "@openrouter/agent";

initLogger({
  projectName: "My Project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = new OpenRouter({ apiKey: process.env.OPENROUTER_API_KEY });
const result = client.callModel({
  model: "openai/gpt-5-mini",
  input: "What is observability?",
});

const text = await result.getText();

Run with the import hook:

node --import braintrust/hook.mjs app.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 and run the compiled file with the import hook, or run TypeScript directly with a TypeScript loader.

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

Manual instrumentation

Trace an OpenRouter Agent client explicitly by wrapping it with wrapOpenRouterAgent.

import { initLogger, wrapOpenRouterAgent } from "braintrust";
import { OpenRouter } from "@openrouter/agent";

initLogger({
  projectName: "My Project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = wrapOpenRouterAgent(
  new OpenRouter({ apiKey: process.env.OPENROUTER_API_KEY }),
);

const result = client.callModel({
  model: "openai/gpt-5-mini",
  input: "Reply with exactly: traced",
});

const text = await result.getText();

What Braintrust traces

Braintrust captures the agent run as a trace tree:

A top-level LLM span for the call, with the final output and aggregated token usage across all turns.
One nested LLM span per agent loop turn, with per-turn input, output, and usage, plus step and step_type (initial or continue) metadata.
One tool span per tool invocation the agent makes, with the tool name, input, and output.

AI providers

SDKs

Developer tools

Runtime environments

Setup

Auto-instrumentation

Manual instrumentation

What Braintrust traces

​Setup

​Auto-instrumentation

​Manual instrumentation

​What Braintrust traces

Setup

Auto-instrumentation

Manual instrumentation

What Braintrust traces