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

Goes beyond the annotations by disclosing what actually changes (humanoid skeleton plus skin weights) and how the result is presented (rendered inline in an interactive 3D viewer), which annotations cannot convey. Weakness: the idempotency_key schema text reveals this creates a *job*, yet the description never mentions asynchronous job behavior or polling via check_job/get_job, and annotations mark idempotentHint=false despite the documented 24h dedupe.

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 core action and effect, no filler. However, "so it can be posed and animated" is stated twice (opening and closing sentence), making the last sentence largely redundant.

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?

With no output schema, the description should explain what is returned; it only says the result is rendered inline, without saying a job reference is returned or how to retrieve it — notable given check_job and get_job are siblings. It also does not state whether the input must be humanoid-shaped for the humanoid skeleton to fit.

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%, so both parameters are fully documented in the schema, including the idempotency semantics. The description only adds the mild hint that the GLB URL may come from the other tools and does not explain format or size constraints beyond the schema.

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 (auto-rig) and resource (static GLB model) and spells out the concrete effect: adds a humanoid skeleton and skin weights. This clearly distinguishes it from siblings like mesh_forge (generation) and refine_model (editing), since it is the step that converts an existing GLB into a posable model.

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?

"Use this when you already have a GLB and want it rigged" gives a clear precondition and intent, and "e.g. one generated by the other tools" hints at the pipeline position. It stops short of naming explicit alternatives or exclusions (e.g. when to use mesh_forge instead), so it is clear context but not full routing guidance.

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