Pi coding agent pulls a 180 and adds MCP support

To maintain minimalism, a new harness layer has been folded into a separate component

The Pi coding agent reached its 1.0 milestone on Thursday while being treated for whiplash.

One of the core new inclusions is support for Model Context Protocol (MCP), which Pi creator Mario Zechner once dismissed as unnecessary.

Earendil, the company formed by Armin Ronacher and Colin Daymond Hanna that acquired Pi in April 2026, explained the about-face by noting that things change.

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Not only has MCP improved, the biz said, but changes the Pi devs implemented in MCP have made integrating other capabilities easier. 

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"For example, the changes we have made to MCP also enable the use of Jev more easily within Pi," the company said, in reference to the widely noted Jev decision model that has already elicited imitations. "Ultimately what Pi needs is quite similar to what MCP needs: a sandbox to play with in the form of an interpreter."

Earendil describes Pi as "a hardened, minimal, extensible agent harness that you can make your own." If Pi were a Python web framework, it would be Flask rather than Django.

Nonetheless, Pi has gained some features. These include Codemode, a harness-side sandbox that helps agents issue tool calls, with support for MCP, decision models, and image models; extension support for virtual models; deferred tool loading; cache warming for Anthropic models; mid-conversation system messages; a new TUI theme; and full-screen mode by default.

Alongside these features, Earendil has built Pi Durable, described as "a new substrate for building long-running agentic applications." It's a distinct component from Pi, the company explained, in order to preserve Pi's minimalist design.

The Pi agent connects the underlying model to tools to manage conversation; Pi Durable represents the layer that orchestrates multiple conversations and handles the storage backend, via SQLite and JSONL.

"Pi Durable is that harness," the company explains. "It does not replace the Pi coding agent. It is a framework for building any agentic application, coding agents included. It shares not only code with the Pi coding agent, like pi-ai, but also its principles: minimalism and malleability." ®