Cycle irregularity check

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

With readOnlyHint, idempotentHint, and destructiveHint already covering safety, the description adds useful behavioral detail: the rule is a stdev/CV/max-length heuristic rather than medical judgment, and irregular results surface a clinician hint. The exact threshold is not disclosed, but the overall behavior is transparent.

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?

Three sentences cover input, output, heuristic, usage order, and clinical caveat with no filler except a harmless version tag. The main input/output statement is front-loaded.

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 analysis tool with two parameters and a simple outcome, the description is nearly complete. It reports the output type and a special-case recommendation for fewer than 3 cycles, though it does not describe the exact return shape or the nature of the 'clinician hint' beyond naming it.

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%, so the baseline is 3. The description reinforces the 3+ day meaning of cycle_lengths_days but adds no new information about privacy_mode or value formats beyond what the schema already documents.

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 names a specific verb ('reports') and resource ('last 3+ cycle lengths'), and states the exact output type ('regular or irregular'). It also names the underlying heuristic, which sets it apart from cycle_estimate_phase, cycle_predict_next_period, and other sibling tools.

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?

It gives an explicit invocation context: 'Use this BEFORE deciding whether to set cycle_irregular: true on the other tools.' It also clarifies a limitation ('NOT a clinical diagnosis') and the 3+ length prerequisite, though it does not name alternative tools to use when a different question is being asked.

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