a11y-toolkit: WCAG criterion explained

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

Annotations already mark the tool read-only and idempotent; the description adds that it is a knowledge lookup and does not fetch or audit anything, which is useful beyond the safety hints. It also discloses what the returned explanation covers (requirements, failures, verification), compensating for the absent output schema.

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 and front-loaded: the first sentence states purpose and content, the second gives concrete use and a behavioral boundary. Every sentence earns its place without wasted words.

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 knowledge-lookup tool, the description covers purpose, output content, language options, when to use it, and the fact that it performs no fetch or audit. With no output schema, this is sufficient for an agent to select and call the tool correctly.

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 schema already documents code and lang with an example and enum. The description reinforces the expected format with several criterion codes and mentions es/en, but adds only marginal value beyond the schema.

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 states a specific verb and resource: it explains a WCAG 2.2 success criterion in plain language, covering requirements, typical failures, and toolkit verification. It also distinguishes itself from the sibling audit tools by explicitly saying it is a knowledge lookup and 'does not fetch or audit anything.'

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 clear when-to-use guidance: 'Use it whenever you need to explain WHY a finding matters or what the criterion actually says.' It does not explicitly name alternatives or give when-not-to-use conditions, but the knowledge-lookup note and sibling list make the boundary clear.

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