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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false), so the description adds useful context beyond them: files are bundled 'unchanged', nothing is converted, and the 1-50 file limit is stated. It does not describe the return format or what happens if the limit is exceeded.

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?

Front-loads the core purpose and packs triggers, exclusion, and limits into a compact block. It's dense (em-dash fragments) but every clause carries information; minor redundancy on the file-count limit repeated from the schema.

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 utility with no output schema and full schema coverage, the description covers purpose, triggers, exclusion, and constraints. Only return-value behavior is unaddressed, which is a minor gap given the tool's simplicity.

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 (name, files) are already documented, including defaults and accepted id forms. The description echoes the same 1-50 limit and file sources without adding new syntax or format detail — baseline 3 applies.

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 specific verb (zip/bundle) and resource (files into one .zip archive) and explicitly contrasts with the sibling convert_batch and its non-converting nature. An agent can distinguish it from convert_* and files_unzip without opening schemas.

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?

Explicit trigger phrases ('zip / bundle / archive / put them all in one file') plus the delivery use case (several results as one attachment), and a named alternative condition ('for converting many files use convert_batch'). Nothing is left to inference.

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