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

Annotations already declare readOnlyHint=true, openWorldHint=false, idempotentHint=true, and destructiveHint=false. The description adds meaningful behavioral context beyond that: it preserves bytes and nested safe paths, and rejects traversal, duplicate/colliding names, and excessive data. This tells the agent what input patterns will fail, which annotations alone do not provide.

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 two dense sentences with no filler. The primary action is front-loaded, and the second sentence efficiently lists the behavioral constraints. Every phrase contributes useful information.

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 the description does not need to explain return values, and the annotations cover safety and idempotency. The description is nearly complete for calling the tool correctly: it explains input shape at a semantic level and rejection rules. It could be slightly more complete with explicit guidance on the maximum file count or size limits, but the schema already encodes those as maxItems and maxLength.

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 description must carry the semantic burden. It clarifies that each file has a caller-supplied 'name' and UTF-8 'text', that names may represent nested safe paths, and that path traversal and duplicate/colliding names are rejected. It does not mention the exact size/count limits, but the schema encodes those structurally and the description adds the important semantic constraints.

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 states a specific verb and resource: 'Create an exact ZIP of caller-supplied named UTF-8 texts.' It is immediately distinguishable from the sibling conversion tools (csv_to_xlsx, markdown_to_pdf, etc.) because it packages caller-provided texts into a ZIP rather than converting between file formats.

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 usage context clear: the caller supplies named UTF-8 texts and no external files or fetches occur. It does not explicitly name alternatives or state when not to use this tool, but the 'No external files or fetches' exclusion gives strong guidance for an in-memory ZIP creation scenario.

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