get_heart_rate_zones

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds return-content context (DEFAULT plus per-sport profiles), but nothing about auth, whether an empty result is possible when zones are unconfigured, or how profiles are structured. Useful but thin addition over the annotations.

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 short fragment with zero padding, and the most important fact (that multiple profiles are returned) is front-loaded. It is arguably too terse to serve as a full definition, but nothing in it is wasted.

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 and no parameters, the description is the only place an agent can learn what comes back, and it only sketches that (DEFAULT plus per-sport profiles) without describing zone boundaries or what a profile contains. Adequate to recognize the tool, but not complete for an output-bearing read.

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 tool takes zero parameters, so there is no parameter semantics for the description to carry; the baseline for a 0-param tool is 4. The schema simply enforces an empty object with additionalProperties=false.

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 resource (heart-rate zone profiles) and scopes its contents as DEFAULT plus per-sport profiles, which tells an agent what it will get without opening a schema. It lacks an explicit verb, but combined with the name the intent is unambiguous and distinguishable from sibling get_heart_rates (raw samples).

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, and no reference to the sibling tools that operate on the same resource (set_heart_rate_zones, delete_heart_rate_zones, get_heart_rates). The agent must infer that this is the read counterpart purely from the name.

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