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

Beyond the annotations (readOnly=false, idempotent=true, destructive=false), the description discloses a per-call credit cost, a temporary download link with a 15-minute validity, and instructs the agent to always include the link in its reply. This is valuable operational context not present in the schema or annotations.

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: purpose first, then constraints, cost, and return behavior. Each sentence adds operational value, and the agent instruction about including the link is a necessary addition.

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 one-parameter tool with no output schema, the description explains the return format (temporary link, 15-minute validity) and the required agent action. The phrase 'Default output is the zip binary' is slightly ambiguous next to the link-return statement, but the overall picture is sufficient.

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 schema already documents the single `files` parameter and its nested `name`/`content` fields with 100% coverage. The description adds the 'any type' clarification and a folder-name example, but these are marginal beyond the schema, so the 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?

States a clear action ('Create a zip') with a bounded resource ('up to 50 files') and clarifies it packs any file type into a .zip. This is distinct from the sibling PDF/image/validation tools, even though no sibling is named.

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 makes the use case obvious: bundle arbitrary files into a zip. It doesn't explicitly name alternatives or exclusions, but no sibling tool offers zip creation, so the context is clear enough. A 4 reflects clear context without explicit when-not-to-use guidance.

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