“You Said No MCP!”

Pi, the agent harness previously famous for refusing MCP support, now includes it in the core. The developers justify this reversal not by admitting they were wrong, but by arguing that MCP has matured into something closer to OpenAPI with intelligent tool discovery, and that integrating it forced useful architectural changes. Specifically, MCP integration enabled "Codemode," a JavaScript sandbox that runs on the trusted harness side rather than in an untrusted shell environment. This allows agents to orchestrate tool calls with more flexibility and state management, such as using the Jev classifier model to analyze Linear issue tracker data without polluting the main context window.

The post is largely a strategic pivot dressed up as technical evolution. It concedes that MCP remains hard to compose and that many servers still rely on inefficient text dumps rather than structured data, yet argues that embracing the standard is better than standing on the sidelines. The inclusion of Codemode is presented as the solution to these lingering issues, though the claim that this "solves quite a few" traditional problems relies heavily on the success of their specific JavaScript-based approach rather than broad industry adoption. It is a clear admission that their previous stance was static and that they are now willing to trade purity for ecosystem relevance.