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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world behavior, so the safety profile is covered. The description does add genuinely useful context: the calculation method (Naegele's rule) and that trimester milestones are produced. It omits meaningful caveats such as the 28-day-cycle / 280-day assumption that affects accuracy, so it goes beyond annotations but not far.

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?

One sentence, front-loaded with the action and method, with no filler. Every clause (verb, method, return content) 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?

An output schema exists, so return values need not be re-explained, and annotations carry the safety profile. The remaining gap is the crowded due-date/cycle sibling space: without any disambiguation or stated assumption (LMP-based, 28-day cycle), the agent has enough to call it but not to choose it confidently.

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 is fully documented in the schema (YYYY-MM-DD, first day of last menstrual period). The description adds no format, range, or unit guidance beyond that, so the baseline of 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+resource (calculate estimated due date) and adds the method (Naegele's rule) plus the returned artifacts (trimester milestone dates). However, it gives no differentiation from near-duplicate siblings such as calculate_pregnancy_due_date, calculate_ovulation, calculate_menstrual_cycle, or calculate_breeding_due_date, so an agent cannot tell which date tool to pick from the description alone.

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?

There is no when-to-use guidance, no prerequisites (e.g. requires a known LMP date), and no mention of the alternative due-date tools in the sibling list. The agent must infer the use case from the name alone.

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