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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely new behavior: results carry a discount-adjusted price, price-history notes, cross-store duplicates and a tracked buy link, plus the `<store>/<product>` ref format. It stops short of stating pagination, ranking defaults or result caps, which limits it to a 4.

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 front-loaded in the first clause, and the remainder is a dense but non-redundant inventory of what comes back. No filler sentences; the second sentence about the ref format is short and earns its place.

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 carries the full burden of describing returns and does so concretely, enumerating every field an agent would need to reason about (price after best code, price-history notes, other-store availability, tracked link, ref). Nothing essential for calling or interpreting the tool is missing.

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 the schema already explains query, type, store, price bounds, sort and limit in detail. The description adds no parameter-level syntax, format or interaction guidance beyond echoing that products are identified by a ref, 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 verb+resource ("Search the products UK stores sell through Vouchernaut") and scopes the catalogue with concrete examples (flowers, gifts, hampers, candles, homeware). It never contrasts itself with the closest siblings, get_product, search_stores or price_drops, so an agent must infer the boundary, but the core purpose is unambiguous.

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?

There is no when-to-use guidance, no prerequisites, and no named alternative. An agent cannot tell from this text whether to call search_products, get_product or price_drops for a given shopping intent, so routing must come from the tool name alone.

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