calendar_update_event

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

Annotations already indicate this is a mutating operation. The description adds the key behavioral trait that only provided fields are altered, which is important partial-update context beyond what the annotations state. It does not discuss validation or error behavior, but the core transparency is present.

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 description is two short sentences with no filler, and the primary action is front-loaded. Both sentences provide meaningful information: the operation and the partial-update behavior.

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 seven parameters, no parameter descriptions in the schema, and no output schema, this description is too sparse for fully confident invocation. Important details such as the required eventId, default calendarId, and date-time format are left to inference.

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 0%, and the description names no parameters. It does not explain eventId, calendarId's default, or the expected formats for start and end. The description fails to compensate for the lack of schema-level parameter documentation.

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 clearly states a specific operation: 'Change an existing event.' This distinguishes it from calendar_create_event and calendar_delete_event, and the clause 'Only the fields you pass are altered' adds precise update semantics.

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 gives clear context: use this tool when an existing event should be modified, and pass only the fields that should change. It does not explicitly name alternatives or exclusion cases, so it falls just short of the top score.

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