paint_mesh_regions

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

With no annotations, the description carries the full behavioral burden. It does disclose real side effects – it writes a painted 3MF, opens an interactive stage, and auto-decimates oversized meshes – which is genuinely useful. But it omits whether the write mutates an existing design/branch, what preview_only does, and any permission requirements.

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

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

The capitalized INLINE 3D STAGE paragraph largely restates the opening sentence's parenthetical about the orbit/zoom panel and browser stage link. Two paragraphs for a two-clause behavior is poor information density, and the genuinely useful fact (auto-decimation) is buried at the end.

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

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

A 9-parameter mutation tool with a nested assignments object, no output schema, and no annotations needs far more than this. The description says nothing about the required input_path/assignments shape, what the tool returns, or how the painted output is persisted, leaving the agent under-equipped to call it.

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

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

Schema coverage is 56% across 9 parameters, and the description only hints that assignments are keyed 'by name or id.' Nothing explains crease_deg, min_region_area_frac, preview_only, branch_name, or the nested assignments object, so it fails to compensate for the coverage gap.

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

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

States a specific verb and resource: 'Paint mesh regions by name or id and write a painted 3MF.' An agent knows it paints regions and emits a 3MF. However, it never distinguishes itself from close siblings like segment_mesh_regions, paint_decoration_faces, or auto_color_by_region, so routing still requires guesswork.

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

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

There is no when-to-use, when-not-to-use, or alternative-tool guidance at all. The entire second paragraph is spent on the 3D stage experience rather than on helping the agent decide between this and segment_mesh_regions or paint_decoration_faces.

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