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

Annotations declare readOnlyHint=false, so the agent knows this is a mutation (importing events) rather than a safe read, and the description supports that by describing an actual pull. It usefully discloses the return shape ('how many events it brought in, or the error the feed gave'), which annotations do not cover. It does not say how conflicts or duplicates are handled during sync.

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 short sentences, action first, return behavior second. Every clause carries information with 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 compensates by explaining the return value (event count or feed error). Combined with the mutation hint from annotations and the fully documented parameter, it is nearly complete; only sync-conflict behavior is left unaddressed.

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% and the single 'id' parameter is documented in the schema as 'Source id, from list_calendars.' The description adds no format or lookup detail beyond what the schema already provides, so 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 (pull/sync) and resource (one external calendar) with scope ('one', 'now'). It is distinguishable from list_calendars by implying a single-source import action, though it does not name siblings 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?

'Pull one external calendar now' implies an on-demand trigger for a feed sync, which gives some usage context. But it never states when to use this versus list_calendars, add_calendar, or remove_calendar, nor any prerequisites or exclusions.

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