@mastra/braintrust

Braintrust AI Observability exporter for Mastra applications.

Installation

bash

npm install @mastra/braintrust

Usage

Zero-Config Setup

The exporter automatically reads credentials from environment variables:

bash

# Required
BRAINTRUST_API_KEY=sk-...

# Optional
BRAINTRUST_ENDPOINT=https://api.braintrust.dev

typescript

import { BraintrustExporter } from '@mastra/braintrust';

const mastra = new Mastra({
  ...,
  observability: {
    configs: {
      braintrust: {
        serviceName: 'my-service',
        exporters: [new BraintrustExporter()],
      },
    },
  },
});

Explicit Configuration

You can also pass credentials directly:

typescript

import { BraintrustExporter } from '@mastra/braintrust';

const mastra = new Mastra({
  ...,
  observability: {
    configs: {
      braintrust: {
        serviceName: 'my-service',
        exporters: [
          new BraintrustExporter({
            apiKey: 'sk-...',
            projectName: 'mastra-tracing', // Optional, defaults to 'mastra-tracing'
            endpoint: 'https://api.braintrust.dev', // Optional
          }),
        ],
      },
    },
  },
});

Configuration Options

Option	Type	Description
`apiKey`	`string`	Braintrust API key. Defaults to `BRAINTRUST_API_KEY` env var
`endpoint`	`string`	Custom endpoint URL. Defaults to `BRAINTRUST_ENDPOINT` env var
`projectName`	`string`	Project name. Defaults to `'mastra-tracing'`
`braintrustLogger`	`Logger<true>`	Optional Braintrust logger instance for context integration
`tuningParameters`	`Record<string,any>`	Support tuning parameters

Features

Tracing

Automatic span mapping: Root spans become Braintrust traces
Type-specific metadata: Extracts relevant metadata for each span type (agents, tools, workflows)
Error tracking: Automatic error status and message tracking
Hierarchical traces: Maintains parent-child relationships
Event span support: Zero-duration spans for event-type traces
Context integration: Attach to existing Braintrust spans from logger.traced() or Eval()