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

Annotations mark destructiveHint=true, and the description reinforces this by requiring explicit user confirmation before the call. It also discloses the return shape ('Dict with success status and updated event details'), adding useful behavioral context beyond the annotations.

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 compact, front-loaded with the core action, and structured with a summary and a returns note. Every sentence adds practical information: what it updates, the prerequisite lookup, and the mandatory confirmation step.

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 fully described schema, the destructive annotation, and the clear workflow, the description covers the key aspects needed to call the tool correctly. The return note, though brief, is sufficient for invocation since no output schema is provided.

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%, and the parameter descriptions already explain semantics like 'only if changing' and the local-timezone datetime rule. The description adds no significant parameter-level meaning beyond the schema, so the baseline of 3 applies.

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 verb and resource: 'Update an existing calendar event' and specifies the backends ('Outlook or Google Calendar'). It also implicitly differentiates from create_calendar_event by emphasizing 'existing' and the need to search first.

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 an explicit workflow: use search_calendar first, pass the retrieved id, and always ask for explicit confirmation before calling. It does not enumerate when-not-to-use scenarios, but the context and prerequisite are clear.

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