get_activity_hr_zones

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It only states 'Get' (implying a read operation) but omits details about required permissions, response size, or error conditions. For a simple retrieval tool, this is insufficient beyond the basic nature of the operation.

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 short and to the point, with no redundant words. The Args section is slightly redundant with the schema but does not detract. It achieves conciseness while being understandable, though it could be slightly restructured to integrate the parameter description more naturally.

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 tool's low complexity (1 parameter) and the existence of an output schema, the description does not need to detail return values. However, it does not mention that the distribution includes time in zones or other metrics, which would help the agent understand the output format. It is minimally complete but not robust.

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 schema description coverage is 0%, but the description adds 'Garmin activity ID' to the activity_id parameter, providing context that the value must be a Garmin-specific identifier. This adds some meaning beyond the schema's generic 'integer' type, though it does not specify constraints like format or range.

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 'Get heart rate zone distribution for an activity,' specifying the verb 'get' and the resource 'heart rate zone distribution,' which is distinct from sibling tools like get_activity_splits or get_heart_rates. This makes the tool's purpose immediately identifiable without confusion.

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?

The description provides no guidance on when to use this tool over alternatives such as get_heart_rates or get_activity_details. It lacks any context about prerequisites, such as the need for an activity to have heart rate data, and does not mention scenarios where this tool is preferred.

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