Audit Accessibility

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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds useful context beyond that: the checks are deterministic, run at design time, and return 'exact ratios, pass/fail, and fixes' instead of just an audit result. No contradiction 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?

Two dense sentences that front-load the tool's purpose and scope, then provide the alternative. Every clause adds information; there is no fluff or repetition of 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?

Although there is no output schema, the description explains what the tool returns: exact ratios, pass/fail, and fixes. Combined with comprehensive parameter schemas, clear scope boundaries, and an explicit pointer to the alternative tool, this is complete for safe invocation.

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 description coverage is 100%, so the schema already documents all parameters. The description adds meaningful context by specifying platform thresholds (iOS 44pt, Android 48dp, web 24px/44px) and the WCAG 2.2 contrast rules, which directly inform how tap_targets and contrast_pairs are evaluated.

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 and resource: 'Deterministic design-time accessibility checks' for WCAG 2.2 contrast and tap/target sizes. It clearly separates this tool from other design audits and explicitly routes non-mechanical a11y checks elsewhere, making it easy to tell apart from siblings.

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 explicitly defines when to use this tool: the 'machine-verifiable slice of a11y you can run before code.' It also names the alternative for keyboard/screen-reader/Dynamic Type checks with get_design_doc('accessibility'), giving clear exclusion criteria.

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