Check on-page essentials

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

Annotations already declare readOnlyHint=true and openWorldHint=true, indicating a safe, read-only network operation. The description adds context by listing the checks performed, but it does not disclose additional behavioral details like the return format or potential failure modes. Since annotations cover the safety profile, the description's extra behavioral context is modest, warranting a 3 rather than higher.

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 a single sentence that packs in many specific items, but it's not overly long and each item is relevant. It could be structured as bullet points for easier scanning, but the list format is efficient and avoids unnecessary verbiage.

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?

Given the simple input (one URL) and strong annotations, the description fully enumerates the scope of what is checked, giving an agent a complete picture. It does not explain the output format, but since there is no output schema, this is a minor gap. The description is sufficiently complete for the tool's simplicity.

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?

The input schema has 100% coverage for the single 'url' parameter, including a description and example. The tool description does not add further meaning about parameter usage beyond what the schema already provides, so it aligns with the baseline score 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 what the tool does with a specific verb 'Check' and enumerates the exact on-page elements it verifies (title, meta description, H1, canonical, Open Graph, viewport, lazy-loading, image formats, CLS). This list explicitly distinguishes it from sibling tools like check_url_structure or check_rendering, which target different SEO aspects.

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 clear context for when to use the tool: to verify a set of specific on-page HTML essentials. However, it does not explicitly mention alternatives (e.g., seo_full_audit for a broader audit) or specify when not to use it, so it lacks explicit exclusions but gives enough context for an agent to infer appropriate use.

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