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

Annotations already declare readOnly, idempotent and closed-world, so the safety profile is known. The description adds real value beyond that: it says what the scan reports (three error classes, each with a suggested fix) and explicitly bounds the behavior by excluding compilation, which prevents the agent from over-trusting the result.

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 sentences, front-loaded with the action and its target, then the call directive, then the scope caveat. Nothing is redundant with the name or title, and every clause carries 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?

With an output schema present, the description needn't explain return values, and it still characterizes what the diagnostics look like (errors plus suggested fixes). Adequate; only a note on failure/partial-scan behavior would improve 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?

Schema coverage is 100% and the single parameter already documents accepted forms ('a component, a page or a fragment') and the 50,000-character limit. The description repeats none of this and adds no extra parameter meaning, so 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+resource ('Check a Razor snippet's <Dryl…> tags against DRYL's real API') and enumerates exactly what it detects (unknown components, unknown parameters, bad enum values). This is clearly distinct from the siblings, which are lookup tools (get_component, get_tokens, search_components) rather than validators.

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?

Gives an explicit trigger – 'Call it on every DRYL markup you write or change' – and a clear non-goal, 'it does not compile Razor.' It does not name alternatives or spell out when not to call it, but with no competing sibling validator the risk of misuse is low.

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