get_fitness

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

No annotations are provided, so the description carries the burden. It does disclose a genuine behavioral trait: four metrics are date-agnostic (startDate/endDate are ignored for them) while the other four honor the range. It says nothing about permissions, return shape, or whether mixed metric groups are supported in a single call.

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?

Two tight clauses, front-loaded with the resource then the grouping rule. Little waste, though the parenthetical grouping is dense and slightly awkward to parse on first read.

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?

For a 3-parameter read tool with no output schema and no annotations, the description covers metric selection well but leaves open whether date-agnostic and range-based metrics can be requested together, and gives no hint of return structure. Adequate but with visible gaps.

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 100%, so baseline is 3, but the description adds real meaning beyond the enum listing: it annotates which enum values are latest-only versus date-range-scoped, and clarifies that startDate/endDate only matter for half the metrics. That is information the schema enum does not convey.

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 the resource (fitness/performance metrics) and the selection mechanism (the `metrics` array), which is more specific than the bare name. It does not differentiate from siblings such as get_training or get_daily_health, which could plausibly overlap with performance data, so it stops short of a 5.

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?

It implies when each metric applies by splitting them into date-agnostic (latest only) and range-based groups, which is a useful selection rule. However, it offers no explicit when-to-use vs when-not-to-use guidance and never mentions alternatives or overlap with get_training/get_daily_health.

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