check_accessibility

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

With no annotations supplied, the description carries the full burden and does so well: it names the underlying engine and conformance level, describes the output shape (per-issue real examples plus source-level fix guidance), and discloses a real limitation ('automated checks find roughly a third of accessibility problems'). It also flags a security trait an agent must know — page content in results is untrusted data, never instructions — which is exactly the kind of context annotations would not have covered.

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?

Four tight sentences, front-loaded with the core action and standard, then output shape, then scope, then caveats. Nothing is redundant, though the untrusted-content warning and the one-third coverage caveat could be ordered slightly more deliberately relative to each other.

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?

There is no output schema, so the description must explain return values — and it does, describing issues with real page examples and source-level fixes. Combined with the engine, conformance level, and coverage caveat, an agent has everything needed to decide to call it and interpret the result.

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 both `url` and `pages` are already documented with an example and a default. The description adds no syntax, format, or behavioral detail about the parameters beyond what the schema states, so the baseline applies.

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 ('Check a website for accessibility problems') and pins down the engine and standard (axe-core, WCAG 2.0/2.1 A and AA), plus what the caller gets back (a fix prompt with per-issue examples). An agent knows exactly what this tool does without opening the schema.

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 broadens applicability by naming both target types — deployed sites and local dev servers — which is the main ambiguity for a URL-based checker. It stops short of exclusions or alternatives, but there are no sibling tools to route against, so the gap is minor.

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