Check Hreflang

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

The annotations already declare readOnlyHint=true, and the description adds meaningful behavioral context: exactly which validations are performed, that URL accessibility is checked, and that it returns a 0-100 score with per-alternate analysis. This goes beyond the annotation without contradicting it.

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 compact and well-structured: purpose first, then the list of checks, then the output format. Every sentence adds information and there is no filler or redundancy.

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?

For a read-only audit tool, the description covers the input (a URL), the behavior (multiple concrete checks), and the output (0-100 score plus per-alternate analysis), which is especially important because there is no output schema. It provides enough information for an agent to select and invoke the tool correctly. No critical detail appears 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%, with url, timeout, and followAlternates already documented in the input schema. The description provides conceptual context, such as 'reciprocal linking', but does not need to restate parameter details; the baseline of 3 is appropriate.

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 uses a specific verb, 'Validate', identifies the resource, 'hreflang alternate language tags on a page', and lists concrete checks such as ISO 639-1 validity, reciprocal linking, x-default presence, and canonical consistency. This clearly distinguishes it from sibling audit tools like check_links, check_structured_data, or audit_onpage.

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 usage context is strongly implied by the domain-specific first sentence: an agent would know to use this when hreflang validation is needed. However, it gives no explicit when-to-use/when-not-to-use guidance and names no alternatives, so the agent must infer routing rather than being told.

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