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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds value by emphasizing the exact-ID requirement and the pairing of calendar_id with event_id, which is a behavioral constraint beyond the annotations. It doesn't describe return format, but for a simple get operation with no output schema, the annotations plus the ID-pairing warning are sufficient. No contradiction with 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 two sentences with zero waste. The first sentence states the action and required parameters; the second sentence is a critical negative instruction. It is front-loaded with the core purpose and the exclusion is immediately actionable. Every word earns its place.

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 simple read operation with 100% schema coverage and readOnly/idempotent annotations, the description is nearly complete. It covers the key usage constraint (exact IDs, not title/date) and the parameter pairing. The only minor gap is that it doesn't mention what happens if the event is not found or the return shape, but with no output schema and a simple get, this is a minor omission. The account_id disambiguation is handled in the schema, so the description doesn't need to repeat it.

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 three parameters thoroughly. The description adds a concise summary of the key constraint (exact parent calendar_id and event_id) and the 'never by title or date' rule, which reinforces the schema. The account_id parameter is well-documented in the schema with disambiguation guidance. The description doesn't need to add more since the schema is exhaustive.

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 states a specific verb ('Get'), a specific resource ('one event'), and the exact identifiers required ('exact parent calendar_id and event_id'). It also explicitly distinguishes from identifying by title or date, which differentiates it from sibling tools like calendar_list_events or calendar_resolve_event. This is a clear, unambiguous purpose statement.

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 'Never identify an event only by title or date,' providing a clear exclusion. The parameter descriptions further reinforce when to use this tool: use exact IDs from calendar_list_events or calendar_create_event, and never pass title/date. This is strong usage guidance that prevents common agent errors.

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