One day at a glance

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

Annotations already cover read-only, idempotent, non-destructive safety, so the bar is lower; the description adds the non-obvious behavioral trait that sections with no Garmin data are omitted rather than erroring. It also implicitly reveals the composite return payload, which matters given there is no output schema. It does not mention latency or payload size for a multi-section aggregate call.

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?

Three short sentences, zero filler: contents first, use case second, edge-case behavior last. Front-loaded with what the agent needs to decide whether to call it.

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 carries the burden of describing the return value, and it does so by enumerating the response sections to a useful level of detail plus the omission rule. Missing only minor operational details such as payload size or whether sections are nested keys.

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 the single date parameter already documents accepted formats ('today', 'yesterday', 'N days ago') plus local-time semantics. The description adds nothing about the date argument beyond 'for one day', so baseline 3 applies.

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 with scope: 'Everything for one day in one call', then enumerates the exact sections returned (daily summary, sleep, HRV, Body Battery, activities). This clearly separates it from the granular siblings like garmin_get_sleep or garmin_get_hrv, which each cover one of those sections.

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?

Explicitly positions itself as the 'Best first call' for recovery and yesterday-review questions, which is real routing guidance in a 20+ sibling family. It stops short of naming which sibling to use when the agent only needs one section, so the when-not case is only implied.

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