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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavioral context that annotations do not: a rate/cost model ('A few free samples a day, then $0.005 USDC per call via x402'), which tells the agent to expect throttling and payment.

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?

Two compact sentences: the field inventory is front-loaded and the pricing note follows. Dense but every clause is informative, 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?

An output schema exists, so return values need not be re-explained, yet the description still sketches them usefully. For a single-parameter read-only tool with full annotation coverage, this is essentially complete; only usage routing against siblings 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 coverage is 100% and there is a single required 'url' parameter already documented in the schema, so the description carries little additional parameter burden. It adds no syntax or format detail (e.g., scheme requirements) beyond 'Page URL'.

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 title 'On-page SEO audit' plus the description's enumerated outputs (title, meta, H1, canonical, noindex, hreflang, structured data, OG tags, word count, links, alt text, issues, score) make it clear this tool audits a single page's on-page SEO signals. It is distinguishable from seo__links and seo__robots-check by the breadth of the field list, though the description itself is a noun list rather than an explicit verb+resource statement.

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?

There is no guidance on when to use this tool versus the sibling seo__links or seo__robots-check, no prerequisites, and no exclusions. The agent must infer applicability from the field list alone.

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