Weight goals

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

Annotations already declare readOnly, idempotent, non-destructive, open-world. The description adds real value beyond them: the common empty {} return, the raw passthrough format, and the 92-day span cap. It does not describe pagination or error behavior, but for a read-only lookup that is a minor gap.

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 dense sentences, front-loaded with the resource and return shape, then the empty case, then the range constraint. The opening clause is slightly convoluted but nothing is wasted.

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 explaining the return value, and it does so by naming the goal range and the empty-object case. The 92-day limit and period/date alternatives are covered. Only error and edge-case behavior is left implicit.

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%, so the baseline is 3. The description still adds the 92-day maximum span and concrete period examples (last_7_days, last_30_days, this_month), which reinforce the schema's own guidance rather than merely repeating 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 resource (the weight goal in effect over a range) plus what is returned (goal range, as Garmin sends it), and explicitly distinguishes itself from the sibling get_weight by framing the pairing. An agent can tell it apart from get_weight without opening either 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?

Gives clear context: use it alongside get_weight to track progress, and expect an empty object when no goal exists. It also explains the period-vs-start_date/end_date choice. It stops short of explicit when-not-to-use guidance, so it is not a 5.

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