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

Goes far beyond the readOnly/openWorld/idempotent annotations by disclosing the x402 payment flow ($0.03/call, first call returns terms, retry with _meta['x402/payment']), robots.txt obedience, and a ~2-5 s latency budget. These are exactly the traits an agent needs before invoking a paid network call.

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?

Information-dense and mostly front-loaded, but it opens with billing mechanics before saying what the tool does, which delays the purpose statement. The long comma-chain of checks is readable but could be grouped.

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 compensates by describing the return value (score 0-100 with issues and fixes) and the full check inventory. Payment, latency, and compliance constraints are all covered, leaving nothing an agent must guess.

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% for the single `url` parameter, so the schema carries the format detail. The description reinforces scope ('of one URL') and implicitly requires a public http(s) target via the robots.txt note, but adds no new syntax.

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 ('on-page SEO check of one URL') and enumerates the exact checks performed, which clearly separates it from site-wide siblings like seo_audit_lite or site_verdict. The scope word 'one URL' is unambiguous.

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?

Scope implies usage (single page), but it never says when to prefer this over seo_audit_lite or page_quality, nor any prerequisites beyond a public URL. The robots.txt compliance note is helpful context but not routing guidance.

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