Get activity time distribution

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds behavioral detail about the output format (ranges, time, and % of total) and the finer-grained comparison, providing value beyond the annotations without contradiction.

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 exceptionally concise, consisting of two sentences that pack the core purpose and a distinguishing comparison. There is zero fluff, and the key information (what it does, for what scope) is front-loaded. Every sentence earns its place.

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 an output schema present and full parameter documentation, the description is largely complete. It explains the output (histogram with ranges, time, and %), scopes it to one activity, and gives a granularity comparison. It does not mention potential limitations (e.g., activity types), but given the schema and annotations, nothing essential is missing.

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%, so all three parameters are already well-documented in the schema (id, metric enum, bucket_size defaults). The description adds minimal semantic value beyond the schema, mentioning the metric types but not enhancing parameter understanding. Baseline 3 is appropriate given high schema coverage.

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 the verb 'Get' and the resource: how much time was spent at each heart rate, pace, or power level in one activity. It specifies the output (histogram with ranges, time, and % of total) and differentiates from 'time in zones' by noting finer granularity, which distinguishes it from any zone-based tools.

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 clear context by noting 'in one activity' and that it is 'finer-grained than time in zones,' which implies when this tool is appropriate. However, it does not explicitly name an alternative tool or state when not to use it, so it falls short of full explicit guidance.

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