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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so the description doesn't need to repeat safety. It adds real beyond-schema context: cost ('FREE'), that output includes rendered frames plus geometry stats and a plain-language reading, and that any public https .glb is accepted, not just ones made here. It stops short of describing output structure in detail, but that is largely covered by the enumeration of returns.

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?

Front-loaded with the verb, output, and cost, and every sentence adds information about returns, use-case, or scope. Slightly redundant with two separate 'use it' imperatives near the end, which could be merged, but nothing is 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?

No output schema exists, and the description does the work of explaining what comes back: rendered images, triangle/material/texture counts, and an interpretive reading. For a read-only inspection tool with full schema coverage this is close to complete; only fine-grained return formatting is left implicit.

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 100%, with defaults and enums documented for size and views, so the schema carries the parameter burden. The description only echoes scope ('any public https .glb') and 'several angles' without adding syntax or constraint detail. Baseline 3 is appropriate.

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 ('See a 3D model', 'renders the GLB from several angles and returns the frames as images') and explicitly contrasts it with mere linking. It is clearly distinguishable from siblings like mesh_forge or refine_model, which create or modify rather than inspect.

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 ('right after generating to check your own work') and a concrete workflow ('Then regenerate naming the fault you saw'), plus when to apply it ('before you hand it to the user'). It also names the alternative path implicitly – regenerate rather than inspect – leaving little to inference.

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