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

Annotations already cover safety (readOnlyHint, idempotentHint, openWorldHint=false), and the description usefully adds what the tool emits — errors, missing recommended fields, best-practice warnings — plus the no-auth constraint. It doesn't mention size limits or latency, but otherwise adds real context beyond the 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?

Two tight sentences, front-loaded with the verb and scope; the input formats and output contents each get exactly one clause. 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?

With no output schema, the description appropriately summarizes the return payload (errors, missing recommended fields, warnings). The only meaningful omission is input size limits for the 600,000-character cap, which affects failure modes for whole-page HTML.

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 the single 'code' parameter is already documented as accepting JSON-LD, a script tag, or full page HTML. The description restates those same accepted formats almost verbatim, adding no syntax, encoding, or size guidance (the 600k max length is undisclosed).

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?

States a specific verb (Validate) and resource (LocalBusiness structured data), and enumerates the accepted input forms (JSON-LD, script tag, full HTML page). It is clearly a validation tool, but it does not distinguish itself from the sibling validate_page, which an agent could easily confuse it with.

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 implies the use case (checking existing markup before publishing) and notes 'No API key needed', but never states when to pick this over validate_page or generate_schema. The agent must infer routing from the sibling names alone.

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