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

Goes well beyond the annotations: it discloses the immediate effect ('code stops working at once'), that the pass is updated in place rather than re-issued ('Nothing is re-added'), platform scope (iPhone and Android), and a caller-role restriction. These are exactly the operational facts an agent needs before invoking a destructive, idempotent write, which annotations alone only flag but do not explain.

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?

Front-loaded with the effect on the pass and packed with useful detail in five sentences. Slightly overwrought at the tail ('Returns the outcome in one sentence'), which is redundant given the output schema, but nothing else is 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 destructive, role-gated mutation with two params, the description covers effect, reversibility, target selection, authorization, and platform behavior; the output schema carries the return shape, so the brief mention of a one-sentence outcome is sufficient. No material 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 genuine conditional semantics: omitting serialNumber targets the caller's own pass, while supplying it targets a specific pass and requires host or organizer rights. That mapping from parameter presence to authorization scope is not in 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?

States a specific verb and resource ('Voids a Wallet pass on the phone') and immediately names the sibling that reverses it (event_pass_reissue). An agent can distinguish this from event_pass_notice, event_wallet_pass, and event_pass_reissue 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 describes the use case ('For a pass that was photographed or shared, or a guest's pass that a host ... wants voided') and names the inverse tool for undoing it. It also states the permission model that gates the action, so the agent knows when it can and cannot call it.

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