get_sleep_data

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

Annotations already declare readOnly, non-destructive, and closed-world, so the safety profile is covered. The description adds meaningful context beyond that: the data includes a comparison against the user's usual baseline, which tells the agent the output is interpretive rather than raw. It doesn't discuss data availability (e.g., missing nights), keeping it short of 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?

Two tight parts: a one-sentence summary of returned data, then a focused Args block for the single parameter. Front-loaded, no filler, and the wake-up-date clarification is stated before the accepted formats.

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 an output schema present, the description needn't describe return structure, and the sole parameter is fully specified. The only gap is sibling differentiation against get_daily_summary and other daily metrics; otherwise it is complete for a simple single-parameter read tool.

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 0% and the parameter is a bare optional string, so the description carries the full burden — and it does: it defines the anchor as the wake-up date, lists accepted formats (YYYY-MM-DD, 'today', 'yesterday', offset like '-3'), and states the default. This is exactly the guidance an agent needs to avoid the common mistake of passing the sleep-onset date.

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 resource (sleep stages, sleep score, overnight breathing rate and SpO2) scoped to a single night, which is clearly distinct from siblings like get_readiness and get_heart_rate. The verb is implicit but the returned data is named precisely enough that an agent knows exactly what this retrieves.

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?

Implied use case is clear — fetch last night's or a specific night's sleep report — but the description never states when to prefer this over get_daily_summary or other daily-metric siblings, nor any exclusions. Adequate but leaves routing decisions to inference.

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