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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, so the mutation profile is known. The description adds the meaningful lifecycle context that the event is preserved rather than removed, which is the key behavioral distinction from deletion. It does not clarify what a repeated toggle does to an already-set state, which is minor.

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 tight sentences: the action and its state pair come first, then the usage condition and the sibling contrast. No filler.

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 3-param mutation with full schema coverage and no output schema, the description supplies the action, the trigger, and the non-destructive lifecycle. It omits what the call returns or whether the flip direction is inferred from current state, but nothing essential to invoking it is missing.

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 all three params (tripId, variantId, eventKey) are documented in the schema with their source (list_trips/get_trip). The description adds no parameter-level syntax or semantics beyond that, 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?

States a specific verb (flip/toggle) and resource (event) plus the two concrete states it moves between ("we are doing this" vs "just an idea"). An agent can distinguish it from update_event and delete_trip_item without opening any schema.

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?

Explicitly names the trigger condition (user commits to or backs out of an activity) and contrasts it with the alternative delete_trip_item, noting this keeps the event around. When-to-use and when-not-to-use are both covered.

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