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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds the conversion formula and the two return values, but says nothing about input bounds beyond what the schema states or about behavior on extreme inputs — adequate, not rich.

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?

Short and front-loaded: purpose first, then usage, then inputs/outputs, then a cross-reference. The 'See list_bundles' sentence is slightly tangential but short and useful for discovery.

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 single-parameter calculator with an output schema and full annotation coverage, this is nearly sufficient — formula, input, and outputs are all stated. The only real gap is the absence of guidance distinguishing it from the other pet-age calculators in the sibling list.

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 the single parameter already documented as 'Cat age in years', and the description's 'Inputs: cat age years' merely restates it. No additional unit or precision semantics are added, 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 a specific verb and resource ('Convert cat age to human-equivalent years') and even discloses the underlying formula (15+9+4×), which pins down exactly what computation happens. It does not explicitly name sibling alternatives like calculate_dog_age or calculate_pet_age, so an agent must infer differentiation from the word 'feline'.

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 for feline health' gives a topical context but no when-to-use/when-not conditions and no comparison against calculate_pet_age or calculate_dog_age. The pointer to list_bundles is a routing hint, not usage guidance for this tool itself.

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