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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does describe the output ('which is cheaper, price difference, and offers from each source'), but it does not explicitly state whether the operation is read-only, whether authentication is needed, or any limitations such as data freshness or marketplace coverage.

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 description is two concise sentences that directly state the purpose and output. Every word adds value, with no redundant or extraneous 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?

For a simple comparison tool with 3 parameters and no output schema, the description is largely complete: it names the inputs, the action, and the return information. However, it would be more complete with a brief note distinguishing itself from the sibling 'compare_prices' tool.

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?

The input schema has 100% parameter description coverage, so the schema itself provides full parameter semantics. The description adds minimal value beyond echoing that product_a and product_b are specific products or brands, and it does not clarify country formatting or the apparent mismatch where required parameters are marked as required in their descriptions but not in the required array.

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 uses a specific verb 'Compare pricing' with a clear resource ('two specific products or brands') and scope ('across all marketplaces'). It is clear and functional, but it does not differentiate from the similarly named sibling tool 'compare_prices,' which may have overlapping functionality.

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?

The description implies its intended usage: comparing two specific products or brands. However, it provides no explicit guidance on when to use this tool versus alternatives, such as the sibling 'compare_prices,' nor does it state any exclusions.

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