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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety is covered; the description adds the useful behavioral fact that the output feeds compare_prices and that the lookup is exact-identifier based rather than exploratory. It stops short of describing no-match behavior or result ordering, which keeps it at 4 rather than 5.

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 core verb and identifier keys are front-loaded, followed by triggering scenarios, then exclusions. Every sentence carries decision-relevant information – no restatement of the title or filler.

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?

For a 7-parameter read-only search with a full output schema and strong annotations, the description supplies everything the agent needs: matching semantics, usage triggers, exclusions with a named alternative, batch guidance, and the chaining to compare_prices.

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 86%, so brand, condition, price bounds and in_stock_only are already documented at the field level. The description reinforces that query must be a chosen product identifier rather than a category, but adds no per-parameter detail 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 verb (find) and resource (product the user already chose), enumerates the matching keys (exact name, model number, UPC/EAN), and names the downstream consumer of the returned id (compare_prices). An agent can distinguish it from check_recalls and compare_prices without opening any schema.

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?

Explicit when-to-use triggers are given ('ready to buy', 'where to buy', 'best price now', 'is this a good deal', 'a link'), plus when-not ('not for researching what to buy', 'do not use for recall or safety questions – use check_recalls') and the alternative tool by name. It even covers the batch case ('for a parts or shopping list, search each item').

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