TurtlePen / remote MCP + browser WebMCP

Measure it. Place it. Prove it.

The public endpoint serves TurtlePen's complete 73-tool engine with an active document that survives separate API calls. The workspace below is a smaller, visible WebMCP companion for working alongside an agent in ChatGPT's browser; the two surfaces are deliberately named and counted separately.

Public Streamable HTTP

73 canonical tools at one API link.

https://brainn.dev/api/mcp/turtlepen

Connect

Send initialize with Accept: application/json, text/event-stream, then reuse the returned Mcp-Session-Id on every request.

Continue

D1 serializes session versions; R2 restores the document, undo history, saved files, and render artifacts for one idle hour.

Trust the result

The hosted route delegates measurement, L002/L003 text fit, connector labels, and self-contained SVG output to upstream v0.3.2.

Browser companion / 6 page-local tools

Watch a focused WebMCP adapter work on this canvas.

This visible workspace is not the remote 73-tool server. It keeps a compact box-and-connector document in the open page so a browser agent and a person can share the same immediate view.

Live WebMCP surface

A canvas the agent can see with you.

Registering browser tools…

Brainn.dev TurtlePen workspace72 × 34 cells
BriefMeasureRender

Tool contract

turtlepen_help
turtlepen_measure
turtlepen_draw
turtlepen_validate
turtlepen_render
turtlepen_clear

Current validation

CLEAN

1 structural finding. Validation reports; it never silently moves or resizes geometry.

01

Remote MCP

Use the API for the full pen language, pages, shapes, layout, routing, images, glyphs, history, and adjudication.

02

Page WebMCP

Use the visible six-tool adapter when shared browser context matters more than the complete engine.

03

No silent fallback

Tool counts, state ownership, validation depth, and artifact behavior stay explicit on both surfaces.