Sleep

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

Annotations already declare readOnly and idempotent, so the description adds behavioral context beyond them: it clarifies the date boundary ('night ENDING'), introduces the impact of 'today' vs. a calendar date, and warns that detail='full' returns large per-minute series. This provides useful caution for usage without contradicting 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?

The description is two sentences that are packed with useful information and no fluff. The first sentence defines the primary purpose and the key data fields; the second clarifies the 'today' special case and the full-detail trade-off. Every sentence earns its place.

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 tool with no output schema, the description is remarkably complete: it enumerates the fields returned, explains the date interpretation, and flags the payload size for full detail. Combined with rich annotations and a fully covered input schema, an agent has enough context to invoke the 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 100% with descriptions for both 'date' and 'detail'. The description adds further semantic value by explaining the night-ending convention and explicitly linking 'today' to last night's data, as well as stressing the large size of full detail output. This goes beyond the schema's basic format and defaults.

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 clearly states the tool gets sleep data for the night ending on a given date, listing specific metrics like sleep score, time in stages, SpO2, respiration, and heart rate. This specific verb+resource clearly distinguishes it from sibling tools like Garmin's daily summary or HRV tools.

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 provides clear context on when to use the tool: it is for sleep data, and explicitly advises using 'today' for last night's sleep. It does not mention alternatives or exclusions, but the scope is well-defined enough for an agent to select the tool appropriately.

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