lighthouse_audit

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

Annotations only declare readOnlyHint=false, so the description must explain why a read-style audit is flagged as non-read-only. It does so by disclosing that full reports are written to disk, which accounts for the write side effect, and it hints that 'navigation' reloads the page. It doesn't state permissions or report size/retention, leaving a small gap.

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 short sentences: capability, output location, and exclusion/redirection. The scope constraint and alternative are front-loaded with no filler.

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?

With no output schema, the description still tells the agent what comes back (scores, failing audits, flagged DOM nodes) and where full reports go, plus how to get the excluded category elsewhere. Nothing needed to invoke it correctly is missing.

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% and both enums are documented, so the schema already carries parameter meaning. The description's mention of reports saved to disk loosely ties to outputDirPath but adds no syntax or format detail 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?

Names a specific verb and resource and enumerates the categories covered (accessibility, SEO, best practices, agentic browsing), plus explicitly what it excludes (performance). An agent can distinguish it from performance_start_trace and the snapshot/screencast siblings 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?

States the exclusion ('This excludes performance') and names the exact alternative tool and action to take instead ('run performance_start_trace'). Both the use case and the routing decision are explicit.

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