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

Annotations already cover read-only, destructive, and idempotence hints. The description adds valuable non-obvious behavior: optional push notification side effect, the active-pass-only restriction, dual-wallet selection behavior, the passes:manage scope, and the exact OpenAPI route and rate-limit expectations. No contradiction with annotations was found.

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 well-structured and mostly front-loaded: the core operation appears first, followed by constraints, scope, and API mapping. There is minor redundancy between the title line 'Update a pass by serial number' and the first sentence, but overall every piece earns its place and nothing is bloated.

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?

Given 10 parameters, nested objects, no output schema, and notable behavioral nuances, the description covers the essential calling context: field requirements, active-pass restriction, wallet selection, push behavior, scope, and API endpoint mapping. A short note about the return shape or error behavior would make it fully complete, but nothing critical is missing for making the call.

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 important meaning beyond the schema: it states that at least one of data, expires_at, locations, relevant_date, or max_distance is required, which is not obvious from the schema's required list. It also clarifies wallet_type behavior for serials with both Apple and Google passes.

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 clearly identifies a specific verb and resource: updating the dynamic data of an active pass by serial number. It also mentions the optional push notification behavior. It does not explicitly differentiate from the sibling tool updatePass, so it misses the top score for sibling distinction, but the serial-number lookup is specific enough.

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 constraints: at least one update field is required, only active passes are updated, and wallet_type must be used for dual-wallet serials. However, it does not explicitly say when to choose this tool over alternatives like updatePass or when not to use it, so the guidance is implied rather than explicit.

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