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

Annotations only say readOnly=false, idempotent=false, destructive=false; the description adds real behavioral context: a new anchored version is generated, form and materials are carried forward, each refinement becomes a version in a revertable/branchable lineage, and the result renders inline in the 3D viewer. This goes well beyond what annotations provide.

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?

Five genuinely useful sentences, front-loaded with the core action and examples, no filler. The lineage/versioning sentence and viewer-rendering sentence add distinct behavioral value rather than redundancy.

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?

For a tool with no output schema, the description explains input requirements, mutation/versioning behavior, lineage output, and viewer rendering. It doesn't enumerate exact return fields, but the versioning and rendering behavior compensate, and all optional parameters are fully specified in the schema.

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?

With 100% schema coverage, the schema already documents all six parameters. The description adds workflow meaning by instructing to pass the previous model's glb_url and parent_prompt so the change builds on it, and offers plain-language examples for instruction; optional parameters are left to the schema, which already covers them well.

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 ('Iterate on a model') and resource (a previously generated 3D model), with concrete change examples ('make it metallic', 'bigger helmet'). It clearly differentiates from the forge/mesh generation siblings by emphasizing refinement of an existing model rather than creation.

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?

Gives explicit context: use it when you already generated a model and want to describe a change in words, and points to the two key parameters needed (glb_url, parent_prompt). It doesn't explicitly name sibling tools as alternatives or state when not to use, so it stops short of full exclusion guidance.

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