How to Use the Braintrust MCP in Pydantic AI
Run type-safe Braintrust evaluations using Pydantic AI.
Works with every AI agent you already use
…and any MCP-compatible client
Connect Braintrust MCP to Pydantic AI
Create your Vinkius account to connect Braintrust to Pydantic AI and route execution through our secure gateway. The platform manages server hosting, runtime updates, and security layers. Configuration requires no manual server provisioning.
Validate Braintrust prompts in Pydantic AI
Use `list_prompts` to pull versioned system prompts into your agent. Pydantic AI ensures the returned data matches your expected type definitions. If the prompt format changes, your agent throws an error immediately. You catch configuration drift before it reaches your users.
Insert rows with Pydantic AI validation
Call `insert_dataset_row` to save your agent results back to Braintrust. Pydantic AI validates the payload against your schema before the server transmits it. This prevents malformed data from polluting your evaluation records. You get clean metrics every time.
Retrieve ground truth in Pydantic AI
Run `list_datasets` to see which test banks are available for your evaluation run. You select the exact data needed for your current task. Your Pydantic AI agent uses these references to compare model output against known correct answers. It is the most reliable way to benchmark your code.
Set up Braintrust MCP in Pydantic AI
Prerequisites
- Python 3.10+ installed
-
pydantic-ai-slim[fastmcp]package - Active Vinkius subscription with a valid endpoint token
- 1
Install Pydantic AI with FastMCP
Run
pip install "pydantic-ai-slim[fastmcp]". The FastMCP toolset replaces the deprecatedMCPServerHTTPclass with full protocol support. - 2
Configure the FastMCPToolset
Pass a JSON-style config dict to
FastMCPToolsetwith your Vinkius URL. Replace[YOUR_TOKEN_HERE]with your token from cloud.vinkius.com. Supports Streamable HTTP, SSE, and Stdio transports. - 3
Create and run your agent
Pass the toolset to
Agent(toolsets=[toolset])and callagent.run(). Swapopenai:gpt-4ofor any supported model — Anthropic, Google, Mistral, or Groq.
from pydantic_ai import Agent
from pydantic_ai.toolsets.fastmcp import FastMCPToolset
toolset = FastMCPToolset({
"mcpServers": {
"braintrust-mcp": {
"url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp"
}
}
})
agent = Agent(
"openai:gpt-4o",
toolsets=[toolset],
system_prompt="You have access to Braintrust tools.",
)
result = await agent.run("List recent Braintrust transactions")
print(result.output) Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by Braintrust. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.
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Common questions about Braintrust MCP in Pydantic AI
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