Lint markup against the specification

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

The description goes beyond the readOnlyHint annotation by enumerating the specific failure categories it detects, giving the agent a clear sense of coverage. It also explicitly states the tool's advisory nature ('a clean result is not a certificate of accessibility'), which is important behavioral context. No contradictions with 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 compact yet information-dense: two sentences that immediately state the tool's function, list concrete examples of what it catches, and add a crucial advisory. No fluff or repetition.

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 tool's core function, scope, and advisory nature. It doesn't explicitly describe the output format, but the mention of 'a clean result' implies a pass/fail or issue list, which is sufficient for a linter. With only two clearly-schema'd parameters and read-only annotations, the contextual needs are modest.

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 input schema provides full descriptions for both parameters (markup and componentId) at 100% coverage, so the schema carries the semantic weight. The description does not add parameter-level details, but it does provide context about the tool's purpose which indirectly clarifies the markup input. Baseline 3 applies because schema coverage is high.

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 uses the specific verb 'Checks' and clearly identifies the resource (HTML/CSS) and the specific categories of failures (accessibility, design-system). It distinguishes from sibling tools by listing concrete examples, making it clear this is a markup linting tool, not a contrast or theme audit.

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 clearly indicates the tool is for linting markup for specific accessibility/design-system issues, providing context for when it applies. It also includes an advisory that a clean result isn't a full accessibility certificate, which tempers expectations. However, it does not explicitly compare to sibling tools like check_contrast or audit_theme, so it lacks explicit exclusions/alternatives.

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