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

No annotations are provided, so the description carries the full burden. It usefully discloses that no rendering occurs (implying a lightweight, likely read-only pass), but says nothing about required permissions, whether validation is exhaustive, or what the result shape is. Partial disclosure only.

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?

Two short sentences, front-loaded with the purpose before the cost/endpoint note. No filler and nothing 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 single-input validation tool this covers the essentials, but with no output schema and no annotations nothing tells the agent what comes back (a boolean, a list of issues, severity levels) or whether the call is side-effect free. A sentence on the result would close the remaining gap.

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?

Only one parameter, and the schema already documents it fully (GitHub-flavored source, 200KB budget, inline data: images excluded) at 100% coverage. The description adds no syntax or format detail beyond the schema, so the baseline of 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?

Specific verb (Validate) plus resource (markdown document) plus the standard targeted (PDF/UA-1) and the concrete issue classes checked (heading hierarchy, missing alt text). It is clearly distinct from siblings like render_markdown and validate_dsl.

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?

"Cheap — no rendering" signals the context in which this tool is preferred over a render-then-inspect approach, and the API mirror gives an integration cue. It stops short of explicitly naming render_markdown or stating when-not to use it, so it is clear context without exclusions.

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