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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered structurally. The description adds that results are 'summaries' (aggregated, not raw samples) and the endpoint path, but says nothing about pagination, rate limits, auth scopes, or empty-result behavior.

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?

Two sentences, front-loaded with purpose, with the endpoint as a compact second clause. Nothing redundant or padded.

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 read-only GET with fully documented parameters and no output schema, the description covers scope (user + date range) and result type (summaries). It stops short of describing what a summary record contains or behavior on missing data, but nothing an agent needs to invoke it is absent.

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 description coverage is 100%: every parameter (user_id, start_date, end_date, provider) is documented in the schema, including formats and the upstream default for end_date. The description adds no parameter detail 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 and resource ('Get menstrual cycle summaries for a user over a date range') and even pins the underlying REST endpoint, so the agent knows exactly what data is returned. It doesn't explicitly differentiate itself from siblings like vital_get_timeseries or vital_get_sleep, though the resource noun does most of that work.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives (e.g. when to prefer a timeseries endpoint over this summary endpoint). The date-range framing implies usage but the description never states conditions or exclusions.

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