get_hr_histogram

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

With no annotations, the description carries the full burden. It discloses a read-only nature ('Get', 'Analyzes') and describes the return format ('JSON string with HR distribution bins'). Yet it lacks details on bin definition, edge cases (e.g., missing HR data), or other behavioral specifics, leaving gaps.

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, front-loaded with the primary action, and organized with clear Args/Returns sections. Every sentence serves a purpose without redundancy.

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 simplicity (one parameter, output schema present), the description covers the essential aspects: what it does, the parameter, and the return type. It does not explain bin specifics, but the output schema likely provides that structure, making this sufficient.

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 description coverage is 100% (activity_id is already described as 'Activity ID to analyze'). The description merely repeats the parameter and adds 'unique ID', which adds no significant new meaning. The baseline of 3 is appropriate.

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?

Description explicitly states 'Get heart rate distribution histogram for an activity' and elaborates on analyzing time spent at different HR levels. This clearly identifies the resource and action, and the 'HR' specification distinguishes it from sibling histogram tools (power, pace, gap).

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 notes it is 'Useful for understanding cardiovascular load and training zone distribution,' providing clear context for when to use it. However, it does not mention alternative tools or provide explicit exclusions, so it stops short of a 5.

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