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

Annotations already provide readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral detail: unknown IDs return 'found:false' rather than throwing or returning an empty result. There is no contradiction with the 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?

The entire description is one focused sentence. It states the action, the target resource, the lookup key, and the not-found behavior with no filler or redundancy. Every word earns its place.

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 single-parameter lookup tool, the description is complete: it names the input semantics, the operation's scope, and the important edge-case response. An output schema exists, and annotations already capture the read-only, non-destructive nature. Nothing essential is missing for an agent to invoke this 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?

The input schema only provides a bare 'id' field with no description, and schema description coverage is 0%. The description clarifies that the id refers to a model_id, which adds meaning beyond the schema. However, it stops short of describing the expected format or how the model_id should be obtained, so it only partially compensates for the missing parameter documentation.

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 uses a specific verb ('Lookup'), a specific resource ('one Model'), and the lookup key ('model_id'). This clearly distinguishes it from the sibling list/search tools, and the not-found behavior ('Unknown ids return found:false') adds further precision.

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 makes the intended use clear: retrieve a single model by its ID. It signals the relevant situation (you have a model_id) and even covers the edge case of an unknown ID. It does not explicitly contrast with models.list or models.search, but the one-model-by-ID phrasing provides clear contextual guidance.

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