diff_a11y

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

Describes return categories (regressions, fixes, unchanged, net-change summary) and prerequisite that baseline must be saved via audit_a11y, going beyond annotations that already mark it read-only and idempotent.

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?

Three sentences efficiently convey purpose, alternatives, and usage condition without fluff.

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?

Given the tool's complexity (3 params, 2 required, output schema present, annotations present), the description covers when to use, what it does, prerequisites, and return types completely.

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% so baseline is 3, but the description adds critical context that the baseline parameter must be a named baseline saved via audit_a11y, which enhances understanding beyond 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?

Description clearly states 'SECONDARY a11y diff using NAMED baselines' and lists return categories, distinguishing from sibling diff_audits with explicit preference and scope difference.

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?

Explicitly compares with diff_audits ('prefer that') and states condition for using this tool: 'only when you already have a named a11y baseline.'

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