Steps

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely useful behavioral detail: results are one row per day 'as Garmin returns it' (no aggregation or filling), and the 92-day span ceiling constrains how calls must be batched. Missing only whether empty days are omitted or error behavior beyond the cap.

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 return shape, then sibling disambiguation, then the span/parameter constraint. No filler or repeated schema text, and each clause carries new routing or behavioral information.

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 supplies the return fields itself, and for a 3-parameter read-only metrics tool that plus the span limit and sibling routing is everything needed to call it 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 description coverage is 100%, and the enum already lists the accepted period values, so the description's example values (last_7_days, last_30_days, this_month) are largely redundant. It reinforces the period-versus-dates mutual exclusivity and the 92-day cap that already appear in the schema, but adds no new syntax or semantics. Baseline 3 is appropriate.

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+resource ('day-by-day steps over a range') and immediately enumerates the returned columns (calendarDate, totalSteps, totalDistance, stepGoal), so the agent knows exactly what it gets. It explicitly names the two nearest siblings, get_daily_summaries and summarize_wellness, and the condition that separates them.

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?

Gives explicit routing: use get_daily_summaries if you also need floors, calories, HR or stress; use summarize_wellness for weekly/monthly averages over longer spans. It also states the operating limit (max 92 days per call) and the two ways to specify the window (period vs start_date/end_date).

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