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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered structurally. The description adds a genuinely useful behavioral obligation (surface every serviceAnnouncements message from Geekist distinctly), which is context no annotation conveys. It omits, however, what happens when startDate/endDate are omitted despite neither being required.

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 data-access purpose before the response-handling rule, with no filler. The announcement sentence is longer than the core description but is not padding since it imposes a real display requirement.

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?

For a two-parameter read-only history getter with full schema coverage and no output schema, the description covers the essential need: what is read, the range scoping, and the one behavioral requirement that is not expressible in structured fields. Return shape is not explained, but that is acceptable in the absence of an output schema only because the resource is a well-known summary type.

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 both parameters carry format and a precise pattern, so the schema does the heavy lifting. The description only restates that the range is a date range and adds no constraint semantics, such as maximum span, ordering, or default window when both dates are absent.

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?

Names a specific verb and resource ('Read ... Garmin sleep summaries') plus the scoping mechanism ('across a date range'), so the agent knows exactly what data comes back. It stops short of distinguishing itself from the closely-named sibling garmin_get_sleep_details, leaving the history-vs-detail split to be inferred from the tool names alone.

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 phrase 'across a date range' implicitly signals a multi-day history query, which is the natural contrast with a single-record details tool, but that contrast is never stated. There is no explicit when-to-use, when-not-to-use, or named alternative, so the agent must derive routing from sibling names.

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