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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description adds value beyond that by disclosing the required OAuth scope (read:sleep) and the exact REST endpoint it wraps. It does not mention error behavior for an unknown id, which keeps it from a 5.

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?

One front-loaded sentence leads with the core operation before the endpoint and scope metadata. The endpoint and scope lines are compact and useful rather than padding, though they add mild density.

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?

There is no output schema, so the description compensates by naming the payload contents (stage summary, sleep needed, respiratory rate, sleep performance %, start/end) and the auth scope. Nothing essential for correctly calling this one-parameter read 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% and documents the single parameter as a UUID from whoop_list_sleep, so the schema carries the parameter meaning. The description restates 'by its id' without adding format or edge-case detail, matching the baseline for full 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?

States a specific verb (Get) and resource (a single sleep activity) plus the lookup key (id), and the word 'single' implicitly separates it from the sibling whoop_list_sleep. The parenthetical enumerates the returned fields, so an agent knows exactly what it gets back.

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 only implied: 'by its id' signals a keyed fetch, and the schema notes the id comes from whoop_list_sleep, but the description itself never states when to use this instead of whoop_list_sleep or what to do when the id is unknown. Adequate but with a clear routing gap.

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