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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=true, idempotentHint=false, openWorldHint=true), so the description is not the only source of behavioral signal. It adds genuinely new context beyond the annotations: the authentication and membership requirement, plus which fields are optional versus required. It stops short of describing validation rules or whether duplicate events are allowed.

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?

Two sentences, no redundancy, with the action and its scope front-loaded and the prerequisite placed last. Every clause carries information the agent needs.

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 10-parameter create tool with full schema coverage and no output schema, the description covers the action, the field surface, optionality, and the auth gate. The main omission is the return value (e.g. the new event's identifier), which the agent must guess since no output schema exists.

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 every one of the 10 parameters is already documented in the schema, including the subtle local-time-vs-offset semantics of 'date' and the all-day handling. The description adds only a summary list of fields and the optional/required distinction, so the baseline 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 opens with a specific verb and resource ('Creates an event in the selected wedding') and enumerates the payload fields it accepts, so an agent can immediately tell it apart from the update/remove/get/list siblings by their verbs. It does not name a specific alternative, but the create-vs-modify distinction is unambiguous.

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 supplies a real prerequisite ('Requires sign-in and an Aisle membership'), which tells the agent when the call will fail, and the create semantics imply the usage context. However, it never states when to prefer this over update_my_event (existing event) or how it relates to list_my_events, so routing is left to inference.

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