get_performance_trend

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

With no annotations, the description carries the full burden and does a reasonable job: it discloses that the result contains each activity's raw value plus average HR and a regression slope, and warns that no HR normalisation is applied. It omits any note on permissions, limits, or pagination, but for a read-only analytics call this is solid disclosure beyond structured fields.

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?

Front-loaded with the core capability, then the return shape and the normalisation caveat, ending in an Args block. The Args section largely duplicates the schema, making it slightly longer than necessary, but it remains readable and efficient.

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?

An output schema exists so return values need not be spelled out, yet the description still clarifies them (raw value, average HR, slope). Combined with the enum values and the normalisation caveat, an agent has everything needed to call this read-only tool correctly.

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 0%, so the description must compensate — and it does, describing all three parameters including accepted value sets ('pace'/'power', 'running'/'cycling') that are absent from the schema and would otherwise be guesswork. Defaults are also restated, which is redundant with the schema but harmless.

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 names a specific verb and resource ('Get per-activity pace or power over time, with the regression slope') and details the analyzed unit (per activity) and outputs (raw value, average HR, slope). It distinguishes itself from sibling trend tools by being about pace/power movement across activities, though it never names those siblings explicitly.

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?

Usage is implied by the metric/sport framing, and it correctly points to get_athlete_context for HR normalisation — a useful cross-reference. However, it gives no guidance on when to choose this tool versus the many other *_trend siblings (vo2max, hrv, respiration, training_load).

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