SpriteMCP

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open_pixel_editor

Open a local web pixel editor to manually adjust character design layers, then re-compose the character before animation.

Instructions

Open the local manual pixel editor for design layers (human edit gate).

Call AFTER compose_character when the user wants to edit pixels by hand. Opens a small localhost web UI (pencil / eyedropper / eraser) for all 10 EXPORT_LAYER_NAMES. Apply writes design/layers/.png only — never base/. After the user clicks Apply, re-run compose_character before plan_animation. Resolves paths via session output_root / output_dir.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "name": "<name>"
    },
    "name": "open_pixel_editor"
  }
}

Input Schema

Name	Required	Description	Default
`name`	Yes
`port`	No
`output_dir`	No
`open_browser`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.2.0Sep 26, 2026

TDQS

A4.1/5.0

Behavior4/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains that the tool opens a localhost web UI, writes only to design/layers/<layer>.png and never base/, and requires a compose_character re-run after Apply. This is strong transparency, though it does not mention whether the call blocks until the user finishes or what happens with the port/browser options.

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

Conciseness5/5

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

The description is compact and front-loaded with the core purpose, then flows naturally into usage, side effects, and follow-up steps. Every sentence adds necessary information; there is no filler or repetition.

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

Completeness4/5

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

Given that an output schema exists and the tool is a local UI launcher, the description covers the essential workflow, side-effect scope, and path resolution. The main gap is the lack of detail on port and open_browser parameters, but these are optional and less critical to correct invocation.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must compensate for all four parameters. It only adds meaning for output_dir via 'Resolves paths via session output_root / output_dir', and vaguely relates name to 'all 10 EXPORT_LAYER_NAMES'. The port and open_browser parameters are left entirely unexplained.

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?

The description states a specific verb ('Open'), a specific resource ('local manual pixel editor for design layers'), and labels it as a 'human edit gate', which clearly distinguishes it from programmatic pixel-editing siblings like paint_pixels and set_pixels. The first sentence alone is enough for an agent to know what this tool does.

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?

The description gives explicit sequencing: 'Call AFTER compose_character when the user wants to edit pixels by hand' and 're-run compose_character before plan_animation'. This provides clear context for when to use the tool, though it does not explicitly name alternatives or state when not to use it.

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