Icu Get Power Histogram

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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuinely non-obvious context: the result is a distribution of time across power buckets for exactly one activity, which tells the agent what the data represents and that it is scoped per-activity, not aggregate.

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 definition, then a contrast sentence, then example queries. Three short lines with little waste; the closing example phrasing is slightly redundant but earns its place as a routing cue.

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?

Output schema exists and the single parameter is fully documented, so the description needn't explain return values. What remains is the scoping and sibling distinction, both covered. A mention of bucket/zone configuration expectations would round it out, but nothing needed to call it correctly 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?

Only one parameter, and schema description coverage is 100% ('Activity ID to analyze'), so the schema carries the semantics. The description's 'within a single activity' mildly reinforces the scope but adds no syntax or format detail beyond the schema. Baseline 3 applies.

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?

States a specific verb/resource combination: time-in-zone distribution of power within a single activity, plus the output shape in parentheses (histogram buckets, time per bucket). It explicitly contrasts itself with icu_get_power_curves, so an agent can distinguish it from the most confusable sibling without opening a schema.

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?

Names the alternative (icu_get_power_curves) and the condition that selects this tool: 'best efforts across many activities' vs single-activity distribution, reinforced by example phrasings ('how was my workout intensity distributed?'). It gives positive selection criteria but no explicit exclusions (e.g. what to use for non-power histograms, though hr/pace/gap siblings are obvious from names).

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