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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true), yet the description adds real context: the underlying GET path and the concrete failure mode (a missing id yields a 404 GarminHttpError). That error contract is information the annotations do not supply.

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, both front-loaded and load-bearing: the first states what it returns, the second gives the endpoint and error behavior. No filler.

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 could have sketched the returned event fields, which is the main remaining gap. For a one-parameter read tool it otherwise covers identity, endpoint, and error semantics adequately.

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% with a single parameter documented as 'Numeric id'. The description adds only 'by id', which restates the schema rather than clarifying the accepted integer-or-string union or id provenance. 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 and resource with a scoping qualifier ('One calendar event by id'), which implicitly distinguishes it from list_calendar_events and get_all_day_events. It stops short of naming the near-identical sibling get_shared_calendar_event, so an agent must still infer the split.

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?

No explicit when-to-use guidance. The description never says when to prefer this over list_calendar_events, get_all_day_events, or especially get_shared_calendar_event, which shares the same single-event shape. Usage is only weakly implied by 'by id'.

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