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

Annotations already declare readOnlyHint and openWorldHint, so the bar is lower, and the description still adds real behavioral context: documented defaults (numberOfCycles=6, nextReport=false, reportType='CYCLE', todayCalendarDate=today) and the fact that an out-of-range numberOfCycles throws GarminError. This error behavior is genuinely useful and not present in the annotations or schema.

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?

A single dense sentence with the purpose front-loaded and no filler, though the backtick-heavy defaults clause reads as a run-on. Every clause carries information, but splitting defaults from the constraint would improve readability.

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 no output schema, the description would need to say what a 'report' contains, and it does not. It also omits sibling differentiation among several menstrual tools. Safety is covered by annotations and parameters are partially covered, so the definition is workable but leaves notable gaps.

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 only 33%, so the description must compensate, and it does for the key gap: numberOfCycles has no schema description but the text specifies its allowed values {1,6,12} and its default, plus defaults for nextReport, reportType and todayCalendarDate. It stops short of explaining what nextReport means or the full domain of reportType, so it is strong but not complete.

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 ('menstrual-cycle reports') and the scope ('last 1, 6 or 12 cycles'), so the agent knows what it retrieves. However, it never distinguishes itself from close siblings such as get_menstrual_cycle_summary or get_menstrual_calendar_data, leaving the agent to guess which menstrual endpoint to call.

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 or when-not-to-use guidance, and no mention of alternatives despite ~10 menstrual-related siblings. The default values and cycle-count restriction imply how to configure the call, but nothing tells the agent when this tool is the right choice.

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