Structured Data (Schema.org) Check

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

Annotations already establish the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lowered. The description adds meaningful behavioral context beyond that: it discloses that unparseable JSON-LD blocks are 'invisible to search engines' and that the tool reports missing required and recommended rich-result properties against Google's requirements. This describes the checking behavior and its significance without contradicting the read-only, non-destructive annotations.

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 front-loaded with its core purpose in the first sentence, then layers covered types, args, returns, and an example in a logical order. It is longer than typical but the length is justified by the tool's breadth (many schema types and a complex return payload). The Args section is somewhat redundant with the schema, but the Returns section and example earn their place.

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 an output schema present, the description needn't detail return values, yet it still lists the return fields, which is helpful. It covers what is extracted, what is validated, which types are recognized, parameter defaults, and a concrete example. For a read-only analysis tool whose safety profile is carried by annotations, nothing essential for an agent to call it correctly 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 description coverage is 100%, so both url and response_format are already fully documented with type, default, and format details. The description's Args section largely restates the schema rather than adding new meaning, though it does provide an illustrative example invocation. Per the rubric, with high schema coverage the baseline is 3, and the description adds only marginal value beyond the schema.

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 opens with a specific verb+resource pair — 'Extract and validate JSON-LD, microdata and RDFa' — which names both the action and the exact subject matter. The tool title and covered-types list (Article, Product, FAQPage, etc.) reinforce the scope, and the focus on Schema.org structured data clearly differentiates it from siblings like robots_txt_check, meta_tags_check, and sitemap_check, which target entirely different SEO concerns.

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 example ('Does https://example.com/product have valid Product schema?') implies a concrete use case, and the covered-types enumeration hints at when the tool applies. However, there is no explicit statement of when to use this versus an alternative, nor any exclusionary guidance (e.g., 'for general SEO issues use seo_audit'). The usage context is implied but never stated, which is a genuine gap given the 16 sibling tools.

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