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

Annotations already provide readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description reinforces this by stating 'Every call is read-only and idempotent, so after correcting the input it is always safe to retry.' It also explicitly describes error behavior: 'this tool never raises a protocol error — it returns {"error": ...}'. This adds meaningful context beyond the 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 moderately long but well-structured: it starts with the main purpose, then gives a typical input/output, followed by usage guidance and error behavior. Each sentence adds distinct information. While not extremely concise, it is efficient given the complexity of the tool.

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?

The description covers the main use case, error behavior, and return format (verdict, issues, skill_files_found). Given that an output schema exists, the description does not need to duplicate that. It also explains the two marketplace rule sets. Minor gaps (e.g., exact definition of junk files) exist but do not significantly impair completeness.

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 coverage is 100%, so parameters are well-documented already. The description adds value by providing a concrete example ('Typical input {"file_paths": ["my-skill/SKILL.md"], "marketplace": "agensi"}') and clarifying the rules for marketplace values and error handling. This enhances understanding beyond the schema alone.

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 starts with a specific verb and resource: 'Validate a zip layout plan for a skill marketplace before packaging.' It also explicitly distinguishes itself from the sibling 'lint_skill' tool by stating 'Not for the content of a skill file (lint_skill).' This makes the purpose clear and distinct.

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 says 'Use on a planned file layout, before zipping.' It also explicitly states what not to use it for: 'Not for the content of a skill file (lint_skill).' Additionally, it mentions that errors return a helpful message and that the tool is safe to retry, guiding the agent on correct invocation.

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