a11y_compare_browsers

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

With no annotations, the description carries full burden and does substantial work: it declares the output is FACTS only, that axe violations are filtered to browser-unique ones, that missing browsers are installed automatically, that a11y-tree exposure differences are not necessarily bugs, and that it is 'Not a real screen reader.' It omits auth, runtime, and rate-limit context, keeping it from a 5.

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?

Front-loads the highest-value fact (what it returns) in the first clause and stays dense with no filler. Slightly run-on with several semicolon-joined constraints, but every sentence earns its place.

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?

Output schema exists so return format needn't be explained, and the description covers the page-source choice, browser selection, and interpretation caveat well. The only real gap is the undocumented 'level' parameter and any environment/permission expectations.

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 0%, so the description must compensate. It explains browsers (comma list, valid values, minimum 2, auto-install) and the url/html mutual exclusion, but never explains the 'level' parameter (defaults to AA), leaving one of four params undocumented in both schema and description.

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?

Uses a specific verb+resource ('compare... same page in several browsers') and enumerates exactly what it produces: accessibility-tree differences, axe violations unique to one browser, and keyboard focus order per browser. This distinguishes it clearly from siblings like a11y_tab_order, a11y_audit, and a11y_aria_snapshot.

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?

Gives concrete usage constraints: at least 2 browsers, provide EITHER url OR html, missing browsers auto-installed, and a note that interpreting results requires the cross-browser-a11y guide plus user judgment. It lacks explicit pointers to alternative siblings when cross-browser comparison is the wrong choice, so it falls short of a 5.

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