get_activity_series

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

With no annotations, the description carries the full burden and does so well: it discloses the ordering quirk (oldest-first, because Garmin serves newest-first and this 'silently reverses anything treating list position as time'), that include_hr_zones costs one extra Garmin request per activity and is off by default, and that non-triathlon activities come back with sport: null and are dropped when the filter is set.

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?

Front-loaded with purpose, then behaviour, then a clean Args block. The two-sentence pace explanation is slightly editorial but it justifies a deliberate omission, so it earns its place; no filler remains.

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 read-only series tool with 4 parameters, no annotations and an output schema present, the description covers purpose, filtering, ordering, field contents and request cost. Return-value formatting is correctly left to the output schema, so nothing material 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 must supply all parameter meaning, and it does: date formats with inclusive bounds, the allowed sport values, null-sport exclusion behaviour, and the cost/default of include_hr_zones. Nothing an agent needs to construct the call is left undocumented.

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?

The opening sentence names a specific verb (get) and resource (raw per-activity measurements) and pins the scope with 'for a date range, with no interpretation', then enumerates the returned fields. This implicitly separates it from analytic siblings such as get_performance_trend or get_workout_compliance, and from get_activity_details by stating the one-record-per-activity grain.

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?

It gives clear context for when the tool is appropriate ('raw', 'no interpretation', pace deliberately omitted because that's a coaching decision) and explains the sports filter's exclusion semantics. However, it never names an alternative tool or an explicit when-not-to-use condition, so routing still requires inference.

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