Update Calendar Event

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

Annotations already include destructiveHint: true, and the description aligns by stating 'Update an existing calendar event'. It adds the behavioral nuance of partial updates ('Only provided fields are changed'), which is not captured in annotations. This adds value beyond the structured data.

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 extremely concise—two sentences with zero redundant words. The key information ('Update an existing calendar event' and 'Only provided fields are changed') is front-loaded and immediately actionable.

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 straightforward update tool with good schema coverage and annotations, the description is adequate. It covers the core behavior (partial update) and references existing events, but does not mention potential errors (e.g., non-existent event ID) or any validation constraints. However, these are less critical for a simple mutation tool with no output schema.

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?

The input schema provides 100% coverage with clear descriptions for each parameter. The description reinforces that parameters beyond the required event_id are optional and only applied if provided, which is a crucial semantic not fully explicit in the schema. This adds meaning beyond the schema's individual field descriptions.

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 the action ('Update an existing calendar event') and specifies the resource (calendar event). It distinguishes from siblings like create_calendar_event by focusing on existing events. The phrase 'Only provided fields are changed' further clarifies the scope.

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?

The description provides a clear guideline: only provided fields are changed, implying partial update semantics. It does not explicitly mention alternatives or when not to use, but the context of 'existing' implies this is for updates, not creation. It could be improved by explicitly referencing create_calendar_event for new events.

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