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

No annotations are provided, so the description carries the full burden. It clearly discloses the paid nature, the payment amount, and the x402 flow, and it states the tool performs HEAD checks for robots.txt and sitemap.xml. While it doesn't explicitly label itself as read-only, the audit nature and lack of side effects are implied. This is transparent enough but could be more explicit about persistence or side effects.

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?

The description is well-structured: scope, output, usage limits, performance, and payment flow are each covered succinctly in separate sentences. No fluff or redundant information; every sentence adds value.

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?

Despite being a paid tool with a multi-step payment process and several optional parameters, the description gives sufficient context: what it does, what it returns, how many URLs, and how to handle the payment. An agent can correctly invoke the tool without missing critical information.

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 each parameter already has a detailed description. The main description does not add per-parameter semantics beyond the schema (e.g., the payment flow for x_payment is already in the schema). This matches the baseline of 3 for high schema coverage.

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?

The description clearly states the tool audits on-page SEO fundamentals, enumerating specific elements (title, meta description, canonical, Open Graph, Twitter Card, headings, robots directives, viewport, robots.txt, sitemap). This differentiates it from sibling tools like check_links or scan_accessibility, making its purpose 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?

The description provides explicit usage guidance: up to 10 URLs per call, no browser (fast), and a detailed payment workflow via x402 (call once without x_payment to receive challenge, then retry with it). It also explains the output format (prioritised issue list and 0-100 score), which helps agents know what to expect.

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