get_day_detail

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is well covered. The description adds the default-date behavior and the scope of data returned, but says nothing about missing/no-data days, latency, or per-source auth requirements. On net it adds modest context above 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?

Two sentences, front-loaded with the drill-down promise and the content list, and ends with the default behavior where it belongs. Dense but no wasted sentences; the parenthetical event list is justifiable because it defines scope.

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?

An output schema exists so return values need no explanation, annotations carry the safety profile, and the single parameter is fully documented. The description covers purpose and default behavior; only the lack of alternative-routing guidance keeps it short of full completeness.

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% and already documents 'YYYY-MM-DD, today, yesterday'. The description contributes real information the schema does not: the default is null in schema, and it clarifies that an omitted date resolves to today, which changes how an agent should call it.

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-and-resource ('Deeper look at one day') and enumerates the concrete contents: sleep score breakdown, Garmin sleep insight, overnight HRV range, and Body Battery events. That enumeration separates it from summary-level siblings like get_recovery and get_training_summary, even though those siblings are never named.

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 word 'deeper' strongly implies a drill-down from a summary view, and the listed contents imply this covers sleep/HRV/Body Battery rather than body composition or nutrition. However, no explicit when-to-use, when-not-to-use, or named alternative is given, so the routing must be inferred.

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