Activity details

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered. The description adds one piece of real context — that values are Garmin's *computed* summary rather than raw sensor streams — but says nothing about auth needs, rate limits, or behavior for missing/invalid activity IDs. That is adequate but not rich, given the lower bar set by annotations.

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, zero filler, with the scope/value statement front-loaded and the sibling routing immediately after. Every clause earns its place.

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 simple single-ID read tool with full annotation coverage and a field list that effectively previews the return payload, nothing critical is missing. Only absent piece is behavior on invalid/unknown activity IDs in the absence of an output schema.

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 are documented there, including where activity_id comes from and what response_format values mean. The description adds no parameter-level meaning beyond the schema, so the 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+resource ('computed summary for one activity') and enumerates the returned fields (distance, durations, pace/speed, HR, cadence, elevation, training effect, calories). It explicitly distinguishes itself from the closest sibling, garmin_get_activity_splits, so an agent can pick the right tool 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?

The second sentence names the alternative for per-km splits and the condition that selects it, which is exactly the kind of routing guidance needed among the many garmin_get_* siblings. It stops short of saying when NOT to use this tool at all (e.g., raw FIT data vs summary) but the essential fork is covered.

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