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

No annotations provided, so description must disclose behaviors. It does not state the formula (e.g., Karvonen), whether resting_hr is optional, or how zones are labeled. With no annotation safety net, this is insufficient.

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?

Single sentence is highly concise and front-loaded. However, it is perhaps too terse for a tool with optional parameters and an output schema. Some structure (e.g., formula name) would improve clarity without losing conciseness.

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 the existence of an output schema, the description does not need to detail return values, but it should provide enough context for an agent to understand the calculation and when to use it. The current description is vague for a health-related computation with constraints.

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 coverage is 100%, so baseline is 3. The description adds no meaning beyond the schema's parameter descriptions; it does not explain how age and resting_hr interact or what values are typical.

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 the tool calculates heart rate training zones, which is a specific verb-resource pair. It distinguishes from sibling health tools (e.g., calories_burned, estimate_body_fat) by its unique focus, but could be clearer by specifying the number of zones or method.

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 on when to use this tool versus alternatives like calculate_bmr or ideal_weight. Does not indicate prerequisites or exclude cases (e.g., children). The only clues come from parameter names.

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