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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuine context beyond that: the 63-67 day gestation model and the returned due-date window plus milestones. It stops short of 5 because nothing is said about how the window is derived or rounding/edge-case handling.

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?

Four short, front-loaded sentences with the core purpose first and no long prose. 'Inputs: mating date' duplicates the schema and earns little, but the overall size is appropriate and the relevant pointer to list_bundles is kept.

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 an output schema present, return values need not be explained, yet the description still outlines the window and milestones. Combined with annotations covering safety and a fully described single parameter, the definition is sufficient for correct invocation; only explicit selection guidance against related pregnancy calculators is missing.

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 parameter's format (YYYY-MM-DD) is fully documented in the schema. 'Inputs: mating date' simply restates what the schema already provides, adding no format or constraint detail, so this matches the baseline of 3.

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 (Compute) and resource (cat due date) with the decisive domain constraint 'gestation 63-67 days'. The species-specific framing separates it from unrelated calculators, but it does not name a sibling it could be confused with (e.g. calculate_dog_pregnancy or calculate_breeding_due_date), so it falls short of 5.

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 breeders' identifies the intended audience, which weakly implies when the tool applies, but there is no explicit when-to-use, when-not-to-use, or pointer to the dog/breeding alternatives. Usage is implied rather than stated.

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