Get personal bests curves

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

Annotations already cover the read-only, idempotent, non-destructive nature of the tool. The description adds useful behavioral context beyond annotations, such as pace curves including critical speed as a threshold estimate and HR/power curves representing highest averages over durations. It does not contradict the annotations.

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?

Three concise sentences front-load the core operation, add one valuable interpretive detail, and then provide targeted use cases. There is no filler or redundant restating of schema information.

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 rich input schema, output schema, and safety-related annotations, the description is complete enough for an agent to select and invoke the tool correctly. It covers the core purpose, metric families, and typical use cases, while defaults and formats are documented in the schema.

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?

All five parameters are fully described in the input schema, so the baseline is 3. The description adds interpretive context by linking pace to standard distances, HR/power to standard durations, and mentioning critical speed, but it does not materially improve on the schema's already thorough parameter documentation.

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 opens with a specific verb and resource: 'Get personal bests for a sport over one or more periods,' and clarifies the two output families (pace/time vs. HR/power). It is clear and unambiguous, but it does not explicitly distinguish itself from sibling tools like get_activity_best_efforts or get_fitness_summary.

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 gives concrete usage context: 'Use it for PRs, race predictions and fitness progress (compare periods such as 42d vs 1y).' It clearly states when this tool is appropriate, but it does not mention when not to use it or name competing tools.

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