list_activities

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

Annotations already cover read-only, idempotent, non-destructive, open-world, so the description's value-add is the page-size ceiling of 100, the 366-day maximum window, and the fact that dates are interpreted as Garmin-local. Those are genuine constraints beyond the annotations, though result ordering and empty-result behavior remain undisclosed.

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, front-loaded lines with no filler; the hard constraints come first and the caveats follow. The "Units" sentence is terse to the point of ambiguity about which fields it applies to, which is a minor structural weakness rather than verbosity.

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?

An output schema exists, so return values need not be explained, and the description covers the key caller-facing constraints for a paginated list tool with 0% schema description coverage. Gaps remain around offset interplay with next_offset and ordering, but nothing essential to a correct first call is missing.

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 0%, so the description carries the full burden: it clarifies that `sport` is a parent activity type key rather than a subtype and gives examples, and it bounds the date window and page size. `limit` and `offset` semantics are only obliquely implied by "max 100" and "pagination.next_offset", leaving two of five parameters weakly documented.

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 ("List one activity page") plus concrete scope constraints (max 100, <=366 inclusive Garmin-local dates), which an agent can act on immediately. It implies a paged-collection read distinct from the sibling get_activity, but never names or contrasts with that sibling explicitly.

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?

"Follow pagination.next_offset" gives real operational guidance for iterating pages, and the sport note steers callers away from passing subtypes. However, there is no statement of when to use this tool versus get_activity or get_daily_summary, and no prerequisites or exclusions are given.

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