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

Annotations already cover the safety profile (read-only, idempotent, non-destructive). The description adds useful behavioral context beyond that: exact GET endpoint, required scope `passes:download`, the expectation of active-pass state, billing/rate-limit equivalence, and an explicit warning not to invent other paths.

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 compact and front-loaded with the primary purpose. Minor redundancy exists between 'Download a .pkpass file' and 'Downloads the .pkpass binary...', but overall the content is focused and free of 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 simple download operation with only two well-documented parameters, the description is largely complete: it states the return artifact, the active-pass constraint, the required scope, and the exact endpoint. It does not cover error cases or behavior when the pass is inactive, but those are not critical for calling the tool successfully.

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?

The input schema has 100% description coverage for both parameters, so the schema already explains `id` and `x_app_id`. The description adds only a minor semantic cue that the pass must be active, but does not materially expand parameter meaning beyond 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?

The description clearly states a specific action and resource: downloading the `.pkpass` binary for an active pass. It includes the exact operationId and endpoint, but it does not explicitly contrast itself with sibling tools like downloadPassBySerial or downloadSharedPass.

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 implies when to use the tool: when downloading an active pass's `.pkpass` file by ID. It does not explicitly state when not to use it or name alternative sibling tools, though the scope and endpoint mapping provide some operational context.

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