Sleep

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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds genuinely new behavioral facts: long ranges are fetched in chunks automatically and the ceiling is 366 days, which tells the agent about latency and range limits it could not infer from 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?

Two sentences, zero filler. The returned fields are stated first and the operational caveat (chunking, 366-day max) follows, so the most decision-relevant information is front-loaded.

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?

With no output schema, the description responsibly enumerates the returned data (duration, stage breakdown, score, timing). Combined with the range-limit note and full schema coverage, an agent has enough to call it correctly; only the sibling differentiation gap keeps it from a 5.

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 the schema already documents accepted date formats and inclusive end_date defaults. The description only adds the 366-day range cap, which is a limit rather than a parameter semantic; baseline 3 applies when the schema carries the load.

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 gives a specific resource ('per-night sleep') plus the exact metrics returned (duration, sleep stages, score, timing), which is far more informative than the bare title 'Sleep'. However, it never mentions the sibling garmin_get_sleep_detail, so an agent has no stated basis for choosing between two sleep-related 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 date-range nature implies when the tool applies, and the note about chunked fetching of long ranges gives useful operational context. But there is no explicit when-to-use or when-to-prefer-an-alternative guidance, particularly against garmin_get_sleep_detail, which is the most likely confusion point.

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