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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: unknown or private facts are omitted, the operator is an unlicensed referrer receiving a referral fee, and the tools never write, send email or submit enquiries. It does not describe pagination or link format, but the compliance behavior disclosure is substantive.

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 purpose is correctly front-loaded, but the description is a dense paragraph where roughly half the content is legal/compliance boilerplate (referral fees, licensing jurisdiction, Mainland visitors signing in Hong Kong) that is only loosely tied to invoking the tool correctly.

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 does step in to say what is returned ('links') and what is suppressed ('unknown or private facts are omitted'). That covers the return-value gap reasonably, though the locale parameter's effect on returned content is never addressed.

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 coverage is 0%, so the description must carry parameter meaning. It explains the two required params ('by insurer and product slug'), implying slug-style lowercase-hyphen identifiers, but adds nothing about the 'locale' enum parameter or its default, leaving one of three params undocumented in both places.

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+scope: 'Look up one product by insurer and product slug,' which is unambiguous and implicitly contrasts with the sibling compare_products by emphasizing a single product. It does not name sibling tools explicitly, so it stops short of a 5.

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?

Usage is only implied — 'one product' suggests this is the single-lookup path versus compare_products, but the description never states when to use this tool versus that sibling. The rest of the text is compliance/legal framing rather than selection guidance.

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