update_calendar_event

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

With no annotations provided, the description carries the full burden. It does disclose that updates are automatically sent to attendees for organizers, which is a meaningful behavioral side-effect. However, it misses other important behaviors like how recurrence changes apply only to series masters, the risk of overwriting Teams join links, or permission requirements.

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 only two sentences, with the main purpose front-loaded and no filler. Every sentence adds value: one defines partial update scope, the other explains attendee notification 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?

This is a complex tool with 13 parameters, nested objects (recurrence), and no output schema. The description provides only minimal context and does not mention return values, special cases (e.g., recurrence only applies to master events), or the Teams join link warning that exists in the schema. It is not sufficient for an agent to fully understand the tool's behavior and prerequisites.

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 description explicitly states 'Only include fields you want to change', which clarifies that omitted parameters are preserved. This adds critical meaning beyond the schema's property definitions, especially for a tool with many optional parameters. It compensates for the moderate schema coverage (69%) by explaining the update semantics.

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 begins with 'Update an existing calendar event', which uses a specific verb and resource, clearly distinguishing it from creating, canceling, or deleting events. It also explicitly says 'existing', which differentiates it from create_calendar_event.

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 phrase 'Only include fields you want to change' gives clear guidance on partial updates, and 'If you are the organizer, updates are sent to attendees automatically' explains a key behavior. However, it does not explicitly name alternatives or scenarios where another tool should be used, though this is implied by the tool name.

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