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

Annotations only signal destructiveHint=true and readOnlyHint=false, so the description carries meaningful extra weight and delivers. It discloses the invalidation side effects (push notifications to registered devices, immediate appearance in Apple Wallet), the non-fatal failure semantics (rebuild failure still voids at the DB level), the required auth scope, and rate/billing limits. This goes well beyond what the annotations convey, particularly the failure-mode nuance.

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 tight and well-structured: a one-line summary, then distinct sentences for behavior, side effects, failure handling, scope, endpoint mapping, and constraints. Every sentence adds unique, non-redundant information, and critical behavioral details are front-loaded ahead of the operational footnotes.

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 mutation with no output schema, the description covers the essentials: what happens to the pass, the rebuild behavior, push-notification side effects, non-fatal failure, auth scope, and API constraints. Minor gaps remain — it does not describe the response format, nor what happens if the pass is already voided (relevant given idempotentHint=false). These are small but not trivial for an agent deciding whether a retry is safe.

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 both parameters (id, x_app_id) are already fully documented in the schema. The description's endpoint path /manage-passes/{id}/void reinforces that id is a path parameter, but adds no semantic meaning beyond the schema. At 100% coverage, baseline 3 is appropriate.

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+resource ('Void a pass') and explains the mechanism in detail: marks the pass invalidated, rebuilds the .pkpass with Apple's voided flag, and pushes notifications. It maps to a concrete endpoint (POST /manage-passes/{id}/void), making the operation unambiguous. However, it does not explicitly distinguish itself from its closest sibling voidPassBySerial, so an agent must infer the by-ID-vs-by-serial difference from the parameter and path.

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 provides useful operational context: required scope (passes:manage), the OpenAPI operation mapping, and reminders about standard billing/rate limits and not inventing paths. But it never states when to use this tool versus alternatives — notably voidPassBySerial, which performs the same action by a different identifier. The usage window is left implicit in the 'id' parameter rather than being made explicit.

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