Get a Garmin day

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

Annotations already establish this is a safe read (readOnlyHint=true, openWorldHint=false), so the description only needs to add context — and it does, notably the non-obvious semantics that sleep is keyed by this wake-up date and that calories include intake only when food is logged. It stops short of describing response shape or any data-availability caveats for missing days, which keeps it a 4 rather than 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?

The front-loaded purpose clause is followed by a dense but purposeful field inventory, then two short routing sentences. The metric list is long, yet every item earns its place as coverage disclosure given there is no output schema; slightly tighter grouping would make it a 5.

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 and no structured return documentation, the description carries the burden of telling the agent what comes back, and it does so comprehensively while also handling the cross-date sleep-keying trap and the compound use case. Nothing an agent needs in order to call this correctly is absent.

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 single date parameter is already documented with its format and 'default: today in the user's time zone' behavior, so the baseline is 3. The description adds only indirect guidance about which dates to request, not new meaning about the parameter itself.

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 names a specific verb and resource ('One day at a glance') and then enumerates the exact metrics returned — resting heart rate, Body Battery, stress minutes, intensity minutes, steps, calories, hydration, HR alerts, sleep and HRV. That enumeration makes it distinguishable from garmin_get_daily_summaries and the single-metric siblings without opening any schema.

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?

It gives explicit when-to-use framing ('for readiness and recovery questions'), a concrete call pattern for a specific decision ('should I train hard today?' → call for today and yesterday), and routes to named alternatives for detail (garmin_get_sleep, garmin_get_hrv, garmin_get_activity). Both the positive case and the handoff case are stated.

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