MCP is all you need — Samuel Colvin, Pydantic
Jul 18, 2025 · 15:24
Samuel Colvin, creator of Pydantic, argues that MCP (Model Context Protocol) is all you need for agent-to-agent communication, simplifying what many are overcomplicating. He explains that MCP's tool calling primitive offers advantages over OpenAPI, such as dynamic tools, logging, and sampling—a mechanism for MCP servers to request LLM calls through the client, enabling nested agentic workflows. Colvin demonstrates a research agent using Pydantic AI that queries the BigQuery public PyPI dataset via an MCP server over stdio, showing how sampling allows the server to generate SQL itself while keeping the main agent's context lean. The demo logs progress to Logfire, an observability platform, and outputs human-readable results. He emphasizes that MCP’s standard I/O mode and extensibility make it ideal for autonomous agents beyond its original desktop coding use case.
