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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the URL is short-lived, it is 'minted at the press' (ephemeral, re-mint rather than cache), and set references collapse into a single ordered ZIP. This meaningfully tells the agent how the result behaves over time.

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?

Three sentences, each carrying distinct information (what it returns, the set/ZIP rule, the caching directive) with the core resource front-loaded. Dense and front-loaded, though 'Minted at the press' is slightly colorful relative to the otherwise plain register.

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?

An output schema exists, so return-shape detail is not owed by the description, and annotations cover the safety profile. The description supplies the operative gaps: prerequisite states, aggregate-set behavior, and ephemerality. The only omission is the optional filename parameter's effect, which keeps it from a 5.

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 0%, so the schema documents structure but not meaning. The description partially compensates by mapping the two accepted reference kinds ('a ready generation or verified upload') onto the reference union, but it never explains the optional 'filename' parameter or what controls the ZIP ordering/naming. Baseline-adjacent, with a partial fill of the coverage gap.

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?

It names the resource (a short-lived attachment URL) and the only two inputs it accepts in domain terms (a ready generation or verified upload), and it explains the aggregate case (a set returns one ordered ZIP). No sibling tool in the list mints download URLs, so differentiation is implicitly clear. It loses a point only because it is phrased as a noun description rather than a direct verb+resource statement.

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 encodes the precondition for use (the generation must be 'ready,' the upload 'verified') and a usage directive ('ask again rather than caching it'), which is genuinely actionable. However, it never names an alternative tool or states when-not-to-use it (e.g., vs get_generation or list_generations for metadata). Usage is implied rather than scoped against siblings.

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