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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds value by disclosing the cost ('$0.03 per call') and the precise return structure (pass bool, violations with id/impact/help/help_url/nodes_affected), which are not covered by annotations or the output schema alone.

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 three concise sentences: purpose, cost, and return format. It is front-loaded with the core purpose and contains no redundant or filler text.

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 tool is simple (accepts url or html), has a full output schema, and the description covers cost and return format. Annotations cover read-only, idempotency, and non-destructive behavior. Nothing critical is missing for an agent to call this 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%, with both 'url' and 'html' parameters clearly described. The tool description does not add extra parameter-specific semantics beyond what the schema already provides, so the baseline score of 3 applies when the schema handles parameter documentation.

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 opens with 'WCAG 2.1 A/AA accessibility audit via axe-core,' specifying the exact domain (accessibility), standard (WCAG 2.1 A/AA), and engine (axe-core). This clearly distinguishes it from sibling tools like audit_performance, audit_security, etc., which target different audit types.

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 states what the tool does but gives no explicit guidance on when to use it over alternatives or when it should not be used. The usage context (accessibility auditing) is implied by the name and description, but no exclusions or references to sibling tools are provided.

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