Earendil · 2026-09-29 · notable
Pi 0.99 — the minimal coding agent adds MCP and a codemode sandbox
Pi v0.99.0 brings MCP into the core of Earendil's terminal coding agent. A new codemode tool runs model-written JavaScript in a QuickJS sandbox, so the model can call several MCP tools in parallel.
Pi's team used to say no to MCP. Version 0.99.0 adds it, with a JavaScript sandbox that composes tool calls.
What is it?
Pi v0.99.0, released on 29 September 2026, lets the Pi coding agent connect to MCP servers over stdio or streamable HTTP with OAuth. In the post 'You Said No MCP', Earendil explains why it changed its earlier position against MCP. The team says the changes MCP needed were 'generally useful' for Pi as a whole.
How does it work?
Codemode is the key piece. Instead of calling one tool per turn, the model writes JavaScript that runs in a QuickJS sandbox inside the harness and calls tools from there, several at once. Codemode loads automatically when MCP is configured, and Earendil treats MCP tools more like an OpenAPI surface that the model discovers through documentation and that returns structured data.
Why does it matter?
Pi is known for its four-tool, small-prompt design, so adding MCP is a real change of direction. Running tool calls as sandboxed code keeps the context small and lets the model combine tools, for example Linear's MCP server with the Jev classifier to score issue sentiment. The same release adds virtual models, which extensions can use to route requests between physical models.
Who is it for?
developers who use or build on the Pi coding agent
Try it
npm install -g --ignore-scripts @earendil-works/pi-coding-agent