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

Annotations only declare readOnly/openWorld/non-destructive; the description adds real behavior the agent cannot infer: it probes conventional paths, the sitemap and on-site links, scores candidates, excludes generic index pages and direct media/PDF links, and returns success=false on failure. That is mechanism, filtering policy and failure semantics in one place.

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?

Five short sentences, front-loaded with purpose and precondition, then mechanism, exclusions, return contract, and the sibling boundary. Nothing is repeated and every clause carries information an agent would otherwise have to guess.

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?

There is no output schema, yet the description documents the return shape (candidate landing-page URL plus discovery details) and the failure case (success=false). Combined with 100% schema coverage on the three inputs, an agent has everything needed to call it and interpret the result.

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 100%, including the enum for offer_type and a detailed topic description, so the schema does the heavy lifting. The description adds only indirect signal ('drives which paths are probed') and no additional format or interaction guidance between domain, topic and offer_type; baseline 3 applies.

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 and resource ('find a specific marketing-offer landing page on a domain') plus the precondition 'when no URL is already known'. The closing line 'It does not create or modify an offer' separates it from the offer-mutation siblings such as create_update_offer and get_offer, and the domain-scoped discovery focus distinguishes it from find_privacy_url.

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?

Gives a clear triggering condition ('when no URL is already known') and an implicit exclusion via the negative statement about not creating/modifying offers. It stops short of naming the alternative tools (find_privacy_url, get_offer) an agent should fall back to when a URL is already known or an offer must be edited.

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