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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses the bounded single HTML fetch, the opt-in link-checking behavior, and the absence of crawling, JavaScript execution, authentication, and stylesheet fetching. These are material behavioral traits an agent needs to set expectations. No contradiction with 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?

Three sentences, front-loaded with the trigger condition, followed by scope, limitations, and authorization constraint. Every sentence adds value and none restate the tool name or title.

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 complete parameter schema, the presence of an output schema, and rich annotations, the description fully covers what the tool does, its safety profile, and its limitations. An agent has everything needed to select and invoke it correctly.

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?

Input schema coverage is 100%, so the parameters are already documented in the schema. The description reinforces bounded behavior and opt-in link checking, but it does not need to compensate for missing schema details. Baseline 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 opens with 'Use this when the user provides one live public webpage URL' and details the specific actions: HTML validation, SEO/accessibility-signal checks, and JSON-LD syntax checks. This makes the tool's purpose and resource unmistakable and separates it from sibling validation tools.

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 gives an explicit trigger condition ('one live public webpage URL'), explicit non-goals ('does not crawl, execute JavaScript, authenticate, or fetch linked stylesheets'), and a hard prerequisite ('only URLs the user owns or is authorized to inspect'). It also notes link checking is opt-in, preventing misuse.

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