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

No annotations are provided, so the description carries the burden. The term 'Validate' and the phrase 'Cheap — no rendering' strongly imply a read-only analysis with no side effects, though it does not explicitly state that no data is modified. This is sufficient for a validation tool.

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 concise and well-structured, covering the action, target, specific checks, a cost/behavior hint, and an API mirror reference in two sentences. No redundant information is present.

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 validation tool with a single parameter and no output schema, the description is complete. It mentions the API endpoint for traceability and gives a hint about performance, which is sufficient context for an agent to decide to call it.

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 description coverage is 100% for the single parameter, and it already specifies 'GitHub-flavored markdown source.' The tool description does not need to add further parameter details, so a baseline score of 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?

The description clearly states the verb (Validate), the resource (a markdown document), and the specific checks performed (PDF/UA-1 accessibility issues: heading hierarchy, missing alt text). It also distinguishes the tool by noting it is cheap and does not render, which helps differentiate from sibling template-management tools.

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 gives usage guidance by explicitly stating it is cheap and does no rendering, implying it should be used for quick validation without rendering overhead. While it does not name alternative tools for when not to use it, the context of siblings (template operations) makes the intended use clear.

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