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

Annotations only give generic hints (readOnlyHint=false, openWorldHint=true, non-idempotent), but the description goes well beyond them: it discloses that without an API key nothing is generated until the user clicks, that API-key mode spends the caller's credits, the required `Authorization: Bearer pp_live_…` header, and the returned `generation_uid`. No contradiction with annotations.

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?

Three dense sentences, all front-loaded: capability first, then the two modes, then the routing to the parametric CAD sibling. Every clause carries decision-relevant information (auth, credits, return shape, domain of suitability) with no filler.

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 generative, side-effecting tool with no output schema, the description covers what an agent needs: input modes, auth requirements, credit consumption, the concrete return value, and how to poll the result. Nothing material is missing.

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 description coverage is already 75% and covers `prompt` and `quality`. The description adds genuinely new semantics by restricting `image_url` to API-key mode and clarifying that the tool accepts either text or image input. It doesn't discuss `format` values or the cost tiers of `quality`, so not a 5.

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+resource ('Turn a text prompt or an image into a print-ready 3D mesh') and names the output geometry formats (STL/GLB/OBJ). It explicitly distinguishes itself from the sibling `design_parametric_cad` for exact-dimension mechanical parts, and names `check_3d_generation` as the follow-up tool.

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 when-to-use routing: text/image-to-3D here vs. `design_parametric_cad` for dimensioned parts. It also spells out the two operating modes (no API key = prefilled link only; API key = real job submitted and credits spent) and the condition that selects each.

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