The irritation
Browser agents can complete increasingly sophisticated tasks, but few experiences invite people and agents to meet as equal players inside a fast, social game.
GamePrototypeBuilt August 2026
MCPencil
A real-time Pictionary-style party game where people and WebMCP browser agents sketch, guess, and compete in the same room.
- Current state
- Prototype — Built August 2026
- Jack’s role
- Concept, Game design, Full-stack engineering, Agent interaction design
- Find it in the workshop
- Prototype Bench · MCPencil drawing table
Built because…
The real build story.
What I built
I built a real-time Pictionary-style party game with a React and TypeScript interface, an SVG drawing canvas, and three ways to play: Sketch Duet, Team Match, and Free-for-All. Humans use the browser interface while WebMCP agents join through purpose-built game tools.
The hard part
The same rapid draw-and-guess loop has to make sense through human pointer controls and semantic agent actions while strokes, turns, guesses, timers, and scores stay synchronized for every player in the room.
Under the casing
Proof, not decoration.
Build evidence03 items
- Sketch Duet, Team Match, and Free-for-All modes for human and agent players
- A real-time SVG canvas and guessing loop synchronized through WebSockets
- Cloudflare Workers, Durable Objects, and SQLite coordinating persistent party rooms
- React
- TypeScript
- SVG Canvas
- Cloudflare Workers
- Durable Objects
- SQLite
- WebSockets
- WebMCP
Scope of work
What I owned.
- Concept
- Game design
- Full-stack engineering
- Agent interaction design
No victory-lap math
Outcome and lesson.
Where it landed
MCPencil is a free experimental prototype built in August 2026. Cloudflare Workers, Durable Objects, SQLite, and WebSockets keep each party room live while humans and browser agents play together.
What stayed
Agent-native interaction becomes easier to understand when agents enter a familiar set of rules. A party game makes tool calls visible, social, and immediately testable instead of hiding them behind background automation.
This project has a physical address.
In the playable workshop, MCPencil lives in the Prototype Bench as a mcpencil drawing table. You can inspect it without unlocking anything.