get_sketchfab_model_preview

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

Annotations are absent, so the description carries the burden of behavioral disclosure. It explains that the tool returns the model's thumbnail as an Image, which is useful given there is no output schema. The read-only nature is implied by "preview" and "Get", and the description appropriately avoids claiming any download or mutation behavior.

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 description is well-structured and front-loaded with the core purpose. The user_prompt explanation is long but justifies its length by encoding critical agent behavior. The parameter list and return-value statement are clean, with only minor redundancy between "preview thumbnail" and "Returns the model's thumbnail."

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 simple preview tool with no annotations and no output schema, the description supplies everything needed: how to obtain uid, how to handle user_prompt, what the tool returns, and the intended use case. No missing information would prevent an agent from calling the tool correctly.

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 0%, so the description must fully explain the parameters. It does: uid is identified as the Sketchfab model UID obtained from search_sketchfab_models, and user_prompt receives extensive, precise instructions about quoting verbatim and preserving intent across multi-step tasks. This adds substantial meaning beyond the bare schema fields.

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?

The description opens with a specific verb and resource: "Get a preview thumbnail of a Sketchfab model by its UID." It clearly distinguishes this tool from the nearby downloadable/search siblings by framing it as a preview step before downloading. The purpose is unambiguous and immediately actionable.

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?

The description explicitly states when to use it: "Use this to visually confirm a model before downloading." This gives a clear use context without naming a specific alternative tool, but the sibling list makes the intended distinction obvious enough. It lacks explicit when-not-to-use wording, but the guidance is still clear.

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