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

The annotations already declare readOnlyHint, idempotentHint, non-destructive behavior, and closed-world scope. The description adds useful domain behavior beyond the annotations: the 63-day gestation assumption and that the tool returns a due date window plus milestone dates. An output schema exists, so it need not spell out the exact return shape.

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 short and front-loads the core computation and input. The final cross-reference to list_bundles is slightly incidental but still relevant to the calculator bundle context.

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 one-parameter calculator with full schema coverage and an output schema, the description supplies the key domain assumption (63-day gestation) and output expectations. It does not need to explain return values because the output schema covers them.

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?

There is only one parameter and schema description coverage is 100%, so the schema already documents mating_date and its YYYY-MM-DD format. The description names 'mating date' as the input but adds no further semantics, which is acceptable at the baseline for a fully documented single parameter.

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 states a specific verb and resource: compute a dog due date from a mating date, with the 63-day gestation period made explicit. It distinguishes dog pregnancy from cat pregnancy by name, but does not explicitly differentiate it from sibling tools such as calculate_breeding_due_date.

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 phrase 'Use for breeders' gives implied audience context, but the description does not state when to choose this tool over calculate_breeding_due_date or other pregnancy-related calculators. No exclusions or alternatives are provided.

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