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

The description goes well beyond the annotations by disclosing PATCH semantics, attendee-list replacement, automatic sendUpdates=all notifications, account-linking requirements, default account selection, and the success return shape. These are exactly the non-obvious behaviors an agent needs to predict side effects.

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?

Five dense sentences with no filler. Purpose is front-loaded, and each sentence earns its place: semantics, side effects, prerequisites, default behavior, and return value.

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 9-parameter mutation tool with no output schema, the description covers everything needed to call it correctly: prerequisites, defaults, PATCH behavior, attendee side effects, and the success response. No obvious operational gap remains.

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 coverage is 100%, so the baseline is 3, but the description adds important cross-parameter meaning: only provided fields are changed, attendeeEmails replaces the whole list and triggers notifications, and googleAccountId defaults to the first connected account. This is meaningful value beyond the schema.

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 opens with a specific verb and resource: 'Update (reschedule) an existing Google Calendar event.' This clearly identifies the operation as a mutation on an existing calendar entry and distinguishes it from sibling tools like create_calendar_event and delete_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?

It clearly frames the tool for updating existing events and explains PATCH semantics plus the Google-account prerequisite. It does not explicitly name alternatives or state when not to use it, but the context is unambiguous enough that an agent can select it correctly.

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