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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds a genuinely useful interpretive caveat ("does NOT certify identical products") but says nothing about what the comparison returns or how the two result sets are related, leaving the behavioral story thin.

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?

A single compact sentence with the core action front-loaded and the caveat placed second. It is efficient, though verbosity is not the failure mode here – under-specification is.

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 four parameters, 50% schema coverage, no output schema, and no explanation of what a comparison yields (similarity, price delta, matched offers), an agent cannot predict the result shape or how country/max_price apply to both queries. For a non-trivial comparison tool the description leaves too much unspecified.

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 coverage is only 50%: country and max_price carry descriptions, but the two REQUIRED parameters query_a and query_b have no schema description, and the tool description does not compensate by explaining what a "search" string should contain. The description adds no parameter meaning at all.

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 and resource: "Compare two searches using real catalogue results." This is distinguishable from search_deals and get_best_deals by the two-query comparison framing, though it never names a sibling to sharpen the boundary.

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 only implied by the verb and the caveat; the description never states when an agent should reach for compare_deals rather than running two search_deals calls, nor any prerequisites or exclusions beyond the disclaimer.

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