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

Annotations already declare readOnly, idempotent, non-destructive, and non-open-world behavior, so safety is covered. The description adds genuinely useful context beyond that: the data is 'checked daily by MaxWorth' (freshness) and the response includes the comparison page URL. It stops short of describing empty-result or fallback behavior.

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: the resource and scope lead, and the return contents follow. No filler, no restating of the title, and every clause carries information.

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 correctly carries the return-shape burden (rate per portal + comparison URL) and covers the store input implicitly. It is nearly complete, only lacking guidance on zero-match results or how limit interacts with ranking.

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%, so both parameters (store, limit) are fully documented in the schema, including a domain/name example and the 1-5 cap. The description adds no format or matching semantics beyond that, so the 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 resource (current cashback/miles/points rates per online store across named portal families) and the return payload (each portal's rate plus the comparison page URL). This is clearly distinguishable from siblings like search_card_offers and search_cards, which deal with card offers rather than shopping portals.

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 implied by the purpose: look up a store to see which portal pays the best rate. However, there is no explicit when-to-use/when-not guidance and no sibling alternative is named, so an agent must infer the boundary against search_card_offers on its own.

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