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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral facts: a hard cap of 8 results and the specific return fields (ASIN, current price in CAD). It does not mention failure/empty-result behavior for a live external search, which keeps it short of a 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?

Two sentences, front-loaded with the action and scope, followed by the routing condition. The example is short and earns its place by demonstrating the plain-language budget form.

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 single-parameter, read-only lookup with no output schema, the description supplies everything an agent needs: input style, result cap, and the returned fields. Annotations carry the safety profile, so no material gap remains.

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% and there is only one parameter, so the schema already explains that the query is shopper intent in words and may include a budget. The description's example ('power bank under $100') reinforces this but adds no syntax or constraint information beyond the schema (e.g. the 240-character limit is only in the schema). 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?

The description gives a specific verb and resource ('Search Amazon.ca') plus concrete scope: plain-language queries, up to 8 results, each with ASIN and current CAD price. The sibling check_price is not named, but the phrase 'use it when you only have a product name' implies the distinction (check_price presumably works from an identifier), so differentiation is present but indirect.

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?

It states a clear selection condition: use this when you only have a product name, which is the inverse of needing an ASIN for check_price. There is no explicit exclusion or statement of what to do when the query returns nothing, but the positive guidance is unambiguous.

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