get_hr_zones

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

With no annotations, the description must fully explain behavior. It says 'Calculates' but does not disclose that it likely relies on stored athlete profile data (since there are no parameters), nor does it describe the output format or any side effects. The source of 'LTHR & Max HR' is ambiguous, which could mislead the agent.

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 a single, front-loaded sentence with no filler. It efficiently conveys the core purpose and inputs. Every word contributes value.

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 tool with no output schema, no annotations, and zero parameters, the description is insufficiently complete. It does not explain where LTHR and Max HR come from, what the 'breakdown' looks like (e.g., bpm ranges), or how to interpret the result. This lack of context could hinder correct invocation and result handling.

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?

There are zero parameters, and the schema has no descriptions, so the baseline is 4. The description adds meaning by specifying that the calculation is based on LTHR and Max HR, which clarifies the implicit inputs even though they are not formal parameters.

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 clearly states a specific action ('Calculates') and resource ('athlete 5-zone HR breakdown') with explicit inputs ('based on LTHR & Max HR'). This distinguishes it from sibling tools like get_pace_zones, which focus on pace rather than heart rate.

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 about when to use this tool versus alternatives such as get_pace_zones or calculate_vdot. There is no mention of prerequisites, conditions, or exclusions, leaving the agent to infer usage context on its own.

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