Get Garmin activity details

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered; the description adds real value by enumerating exactly what comes back (summary metrics, split summaries, structured workout, multisport parent/child IDs) — understanding that the payload can be large and nested. It omits any note on auth, rate limits, or behavior for invalid/expired activity IDs, which keeps it below a 5.

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?

The purpose and the usage chain are front-loaded, which is good, but the return-value sentence is a single very long parenthetical enumeration of ~20 metrics. That wall of field names is informative yet poorly structured — it would read far better as a short list or a note pointing to response_format='json' for the full structure.

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?

There is no output schema, so the description must carry the return shape — and it does, itemizing metrics, splits, workout, and multisport IDs. Combined with the ID-source guidance and the response_format hint, an agent has everything needed to call this correctly on the first try.

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, so the baseline is 3. The description adds the provenance of activity_id ('from garmin_list_activities'), which tells the agent where the value must come from — genuine meaning beyond the schema's 'e.g. 12345678901'. It says nothing extra about response_format beyond what the enum already conveys.

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 ('Get full details for one Garmin activity') with an explicit scoping constraint ('by ID'), which cleanly separates it from garmin_list_activities, garmin_get_activity_laps, and garmin_get_activity_streams. An agent can place this tool without opening any 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 the prerequisite explicitly ('Get IDs from garmin_list_activities') and a concrete chain example ('Tell me about yesterday's run' -> list, then call this with its id). It does not say when to prefer garmin_analyze_activity, garmin_get_activity_laps, or garmin_download_activity_fit instead, so the sibling differentiation stops short of full routing guidance.

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