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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description goes beyond that by adding 'deterministic checks,' listing the check categories, stating the output format ('every finding with an explanation and a fix'), and adding 'stores nothing' — a new behavioral detail not covered by the annotations. It consistently reinforces the read-only nature without contradicting the structured hints.

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 three sentences with zero waste. The core purpose is front-loaded, followed by scope, output, and safety guarantees. Every sentence contributes necessary information, and there is no redundant fluff.

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 that an output schema exists and the description covers purpose, scope, determinism, output format, and read-only/non-storing behavior, nothing essential is missing for an agent to correctly select and invoke the tool. The description is sufficiently complete for a read-only check of website AI-readiness.

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% for the single 'url' parameter, which already specifies a hostname or full URL. The tool description adds no further semantic detail about the parameter. Since the schema fully documents the parameter, the description's lack of extra parameter information is acceptable, but it doesn't elevate beyond the baseline.

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 and resource: 'Check whether AI agents can read a website.' It then quantifies the scope ('19 deterministic checks') and lists the checked areas (llms.txt, bot policy, structured data, machine endpoints). This is unambiguous and immediately distinguishes the tool from any hypothetical alternative.

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 purpose is explicit and self-contained, so an agent knows exactly when this tool applies. There are no sibling tools to differentiate against, so explicit exclusions are unnecessary. The description could add a 'not for' hint but the clarity of the use case makes that optional.

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