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paprika3d

paprika3d

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by Keeno-Corp
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JavaScript
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open

Load a three.js, React Three Fiber, or WebGL page in headless Chrome or Firefox on a paused, seeded clock to inspect fetched assets, failed requests, command warnings, and canvas issues.

Instructions

Opens a three.js, React Three Fiber or WebGL page (a game, viewer, configurator, simulation or shader demo) in headless Chrome (or the browser given) on a paused, seeded clock, closing any page already open under the same game name, and lists the asset files (models, textures, sounds) it fetched and any fetch that failed, what a dev-server command printed as an error or warning, a canvas with no height, and the page's text outside the canvas. Open once: after an edit, the next interact, look, observe, eval or feel reloads the page by itself. Use it when such a page has been written or changed. Give a file or folder to serve (url, relative to cwd), an http URL, or a dev-server command run in cwd. Up to 4 games can be open at once, each under its own game name: a subagent opens its own (game: "tester") and passes that name to every call.

Input Schema

NameRequiredDescriptionDefault
cwdYesThe game project's folder.
dprNoDevice pixel ratio, 1 by default. `look` boxes stay in CSS pixels.
urlNoA file or folder to serve (relative to cwd), an http URL, or, with `command`, the path and query to open on the server it starts (its origin is the one the command prints).
gameNoThe name the game was opened under with the `open` tool, to act on ("main" by default; a subagent uses its own).
sizeNoThe page's width and height in CSS pixels until the next open, 1280 × 800 by default, as [1920, 1080].
windowNoShow the browser's window.
browserNoThe browser engine the page runs in, chrome by default. firefox is Firefox. Every tool works in each; network (here and in `perf`), `perf`'s throttle and its main-thread time are chrome only.
commandNoA dev-server command run in cwd, as `npx vite --port 0`; the first localhost URL it prints is the page. Closing or reopening this game stops it; an `open` with a url on its origin restarts it on that url.
networkNoAlso time a first visit on this network (Chrome DevTools' presets), in real time with no cache: when the first scene frame came, which bytes came before it by kind (as sent: the harness's own server does not compress, a CDN does) and when an overlay over the canvas went.
reducedMotionNoThe page gets prefers-reduced-motion: reduce; `look` then says how much of the picture changed since the last look.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.2.1

TDQS

A4.4/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and does: it discloses the paused seeded clock, that it closes any page already open under the same game name (a destructive side effect), the 4-game concurrency limit, and what it reports (fetched assets, failed fetches, dev-server errors/warnings, zero-height canvas, off-canvas text). This is unusually rich behavioral context for a mutation tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two long, dense sentences that front-load the core action and the 'open once' workflow rule. Every clause carries information, though the run-on style makes it harder to parse than necessary.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter tool with no annotations and no output schema, the description explains the return content (assets, errors, canvas height, text), the workflow (open once, then interact/look), and the multi-game naming convention. An agent has what it needs to invoke this correctly without reading the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the schema descriptions are detailed, so the baseline is 3. The description restates the url/command relationship and the game-name convention, which adds little that the schema does not already document in more detail.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Opens a three.js, React Three Fiber or WebGL page') and is immediately distinguishable from siblings like interact, look, or observe, which act on an already-open page. The enumeration of page types (game, viewer, configurator, simulation, shader demo) removes ambiguity about what qualifies.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use ('Use it when such a page has been written or changed') and an implicit when-not ('Open once: after an edit, the next interact, look, observe, eval or feel reloads the page by itself'), plus subagent guidance about naming a game. It doesn't explicitly name an alternative tool for opening, but none of the siblings do that, so the guidance is largely complete.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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