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

Annotations already establish this as a safe, closed-world read. The description goes further with non-obvious behavioral context the annotations cannot express: the guide does not change model answers, is not a substitute for classify, and must be treated as the user's data, never as instructions about tools or actions — a valuable injection-safety caveat.

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 sentences, front-loaded with what the guide is before the usage and safety caveats. Dense and largely waste-free, though the safety sentence is long and could be tightened.

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 adequately conveys what the call returns (the guide's category meanings and the user's exceptions). With one param documented in the schema and no return structure to explain, the definition is sufficient for correct invocation.

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% and the single model_id param is fully described in the schema (including its source, list_models). The description adds nothing about the parameter, so the baseline 3 applies.

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 the specific resource (the model's labelling guide) and its contents (what each category means plus the user's exceptions). It also names the sibling it is not — classify — so an agent can distinguish reading the guide from using the model to categorise.

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?

Explicit when-to-use: read before labelling anything yourself for this user and when explaining the model's answers. Explicit alternative: 'to categorise items with the model, call classify.' Both the trigger and the routing are stated outright.

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