update_calendar_event

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

Annotations only cover readOnly=false, openWorld=true, destructive=false. The description goes well beyond them: it discloses the full GET-then-PUT round trip, that the whole record is rewritten (not a patch), that the server returns no body so the call resolves to null, and that concurrent callers can clobber each other. This is exactly the extra behavioral context the description should carry.

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?

It leads with the key concept 'READ-MODIFY-WRITE' and every clause (field list, null-clears rule, PUT target, null result, concurrency warning) earns its place. It is a single dense, semicolon-chained sentence that is somewhat run-on but wastes nothing.

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 2-param mutation tool with a nested object and no output schema, the description supplies the mechanism, the update semantics, the return value (null), and the concurrency hazard. There is essentially nothing else an agent needs before calling it correctly.

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 only 50% and the schema documents the nested fields without semantics. The description compensates by enumerating the overlayable fields and, importantly, explaining that null clears an optional field — meaning the schema alone cannot convey. eventId is left to the schema, but the added null/overlay semantics lift this above baseline.

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 description names a specific verb+resource and, crucially, an unusual mechanism (READ-MODIFY-WRITE via GET/overlay/PUT). It is unmistakably distinct from siblings like create_calendar_event, delete_calendar_event, get_calendar_event, and list_calendar_events. An agent knows exactly what operation this performs without opening the 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?

It clearly explains how to use it — overlay a set of optional fields and pass null to clear one — which is real usage guidance. It does not, however, explicitly state when to prefer it over siblings or name any alternatives/exclusions, so it stops short of the top bar.

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