update_event

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

No annotations are provided, so the description carries the full burden. It discloses that the tool updates events (mutation), explains the date format inference (datetime vs bare date), notes that all-day end dates are exclusive, and states that property parameters like 'VALUE=DATE' are not accepted and values must not contain line breaks. This is substantial behavioral disclosure, though it doesn't mention conflict detection behavior beyond the etag requirement.

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 concise and well-structured. It front-loads the key guidance ('PREFERRED: Update event fields without iCal formatting') and then provides a clear breakdown of what to use for dates vs other fields. Every sentence adds value, and the structure makes it easy to scan.

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?

Given the tool's complexity (6 parameters, nested fields object, date format nuances), the description is quite complete. It covers the main use cases, the date handling rules, and the constraints on fields. It doesn't explicitly mention return values, but there's no output schema, so that's not a major gap. It could mention what happens if the etag is stale, but the schema already notes it's for conflict detection.

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 100%, so the schema already documents all parameters. The description adds value by explaining the relationship between start_date/end_date/all_day and the fields object, clarifying that dates are handled separately from other properties. It also explains the all-day inference rule and the exclusive end date convention, which goes beyond the schema's basic 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 tool's purpose: updating event fields without iCal formatting. It specifies the exact fields to use (start_date/end_date/all_day for dates, fields for everything else) and lists common properties (SUMMARY, DESCRIPTION, LOCATION, STATUS) plus custom X-* properties. This distinguishes it from siblings like update_event_raw, which likely handles raw iCal formatting.

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 explicitly says 'PREFERRED' and contrasts with update_event_raw, implying when to use this tool vs the raw alternative. It provides clear guidance on when to use start_date/end_date/all_day vs fields, and even notes that all_day is only needed to state intent explicitly. This is strong usage guidance.

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