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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description still adds real behavior: it refuses to mix incompatible products or representative scenarios, which tells the agent failure conditions the annotations do not. It does not say what an 'incompatible' pairing produces or how errors surface.

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 compact sentences, front-loaded with the usage trigger before the limitation. Every clause carries information and nothing is repeated from the schema.

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?

An output schema exists, so return values need not be described, but the tool has four parameters with deep nested objects and low coverage. The description omits what context fields are needed and what happens when scenarios conflict, leaving meaningful gaps for a comparison 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?

Schema description coverage is only 25% across four parameters, and the large nested context object is undocumented. The description adds only the 'scenario-bound' hint and the min-two requirement already enforced by minItems, so it fails to compensate for the coverage gap.

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?

Names a specific verb (compare) and resource (borrowing costs) with clear scope: two or more already-returned products. It implies the discovery-then-compare workflow of its siblings but never names find_borrowing_products or get_product_details to make the distinction explicit.

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?

'Use after product discovery' gives a concrete precondition, and 'two or more returned products' plus the no-mixing constraint set boundaries. It stops short of naming alternative tools or stating when NOT to use it (e.g., for a single product).

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