heart_rate_zones

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

With no annotations present, the description carries the full burden. It fails to disclose the formula used (e.g., Karvonen method), any limitations, or whether the calculation is safe for all users. The behavioral traits of the tool are opaque.

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 concise, with a clear main sentence and a brief parameter list. It front-loads the purpose. However, there is room for a more structured format (e.g., separate sections for use cases).

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?

Given that an output schema exists, the description need not detail return values, but it could clarify what 'heart rate zones' means (e.g., 5 intensity zones). Currently, the agent knows only that zones are calculated, not their structure or application.

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?

The input schema has 0% description coverage for parameters, so the tool description provides essential meaning: 'age — Age in years' and 'resting_hr — Resting heart rate in bpm (default: 60).' This adds value beyond the schema structure.

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 'Calculate target heart rate zones for exercise,' which clearly indicates the tool's function with a specific verb and resource. However, it does not differentiate from sibling tools like bmr_calc or vo2max_calc, which have overlapping health/fitness contexts.

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 guidance is provided on when to use this tool versus alternatives, such as when to choose heart rate zones over other calculations. The description lacks context about prerequisites or expected input ranges.

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