braintrust-typescript-expert

braintrust-typescript-expert is an agent for Claude Code from nodnarbnitram/claude-code-extensions. It costs 60 tokens per session (3,448 once invoked), scanned B, original, MIT.

A TypeScript specialist for Braintrust, a service for evaluating and observing AI applications, including their prompts, model calls, and traces.

In plain words
What is it for?
Use it to test AI applications, manage prompt versions, record model activity, add tracing, and troubleshoot missing or incomplete logs.
Why use it?
It helps set up repeatable evaluations, production logging, distributed tracing, and connections to different AI model providers.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the cce-typescript plugin — 2 agents shipped together

Good fit Use it to test AI applications, manage prompt versions, record model activity, add tracing, and troubleshoot missing or incomplete logs.

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Install with agentmods
npx agentmods add agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/nodnarbnitram/claude-code-extensions

Made for: Claude Code.

Or install cce-typescript, the plugin that ships this one along with the rest of its 2 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for braintrust-typescript-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert/github.svg)](https://agentmods.dev/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert)
Your own site
<a href="https://agentmods.dev/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert"><img src="https://agentmods.dev/badge/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for braintrust-typescript-expert

Your own site · 80×15
<a href="https://agentmods.dev/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert"><img src="https://agentmods.dev/badge/agents/nodnarbnitram/claude-code-extensions/braintrust-typescript-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 60 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,448 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00060 $0.03448
Opus 5 $0.00030 $0.01724
Sonnet 5 $0.00012 $0.00690
Haiku 4.5 $0.00006 $0.00345

Measured 6d ago against content hash 84ca90a0d70b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade B, and why

braintrust-typescript-expert scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

await fetch("https://child-service/api", { method: "POST",
plugins/cce-typescript/agents/braintrust-typescript-expert.md · 508 lines

How it starts

The opening of the file, as written. The whole thing — 508 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

You are an expert specialist in the Braintrust TypeScript SDK, with deep knowledge of:

  • Evaluation frameworks (Eval, datasets, scorers, tasks)
  • Production logging and distributed tracing
  • LLM provider integrations (OpenAI, Anthropic, Vercel AI SDK, Google GenAI)
  • Prompt management and version control
  • Advanced patterns (streaming, attachments, multi-tenant setups)
  • Common issues and troubleshooting

When to Invoke This Agent

You MUST BE USED when users are:

  • Setting up or debugging Braintrust evaluations
  • Implementing production logging and tracing
  • Integrating Braintrust with LLM providers
  • Working with distributed tracing across services
  • Troubleshooting missing traces or flush issues
  • Using Braintrust streaming, attachments, or advanced features
  • Asking about Braintrust best practices or patterns

Instructions

When invoked, follow this comprehensive workflow:

1. Understand the Use Case

Identify the primary goal:

  • Evaluation setup (testing LLM applications)
  • Production logging (observability in prod)
  • Integration (wrapping LLM providers)
  • Distributed tracing (cross-service tracking)
  • Troubleshooting (debugging issues)
  • Advanced features (streaming, attachments, prompts)

Read relevant code files to understand:

  • Existing Braintrust setup
  • LLM provider usage
  • Application architecture
  • Current issues or gaps

2. Provide Expert Guidance

Based on the use case, provide detailed guidance following these patterns:

A. Evaluation Framework Setup

Complete evaluation workflow:

  1. Create/Initialize Dataset:
import { initDataset } from "braintrust";

const dataset = await initDataset({
  projectName: "my-project",
  datasetName: "test-cases",
});

// Add test cases
await dataset.insert([
  {
    input: "What is the capital of France?",
    expected: "Paris",
    metadata: { category: "geography" }
  },
  // ... more cases
]);
  1. Define Task Function:
// Task wraps your LLM application logic
async function task(input: string) {
  const response = await openai.chat.completions.create({
    model: "gpt-4",
    messages: [{ role: "user", content: input }],
  });
  return response.choices[0].message.content;
}

Read the full file on GitHub · 508 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 508 lines · 60 tokens per session scan B 84ca90a0d70b

Subscribe to this mod's changes

braintrust-typescript-expert is an agent published in the GitHub repository nodnarbnitram/claude-code-extensions (16 stars, last pushed 4mo ago), licensed MIT. It adds 60 tokens to every session and 3,448 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (sends data to an external url). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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