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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the four result classifications (documented, conditional, unsupported, unknown), the definition of 'unknown' as lacking publication-approved coverage, and an explicit list of actions it will not perform. Determinism and rate/limit behavior are left implicit but are largely covered by idempotentHint.

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?

Four tight sentences, front-loaded with the core comparison before the scope exclusions and the code-format guidance; no filler. Density is high but every sentence carries information an agent needs.

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 an output schema present, return-value explanation is optional, and the description still usefully names the four result categories. The main gap is that all 8 parameters are optional, yet nothing says how the tool behaves on partial or empty input, nor how confident a verdict is when target_markets or payment_methods are omitted.

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 0% across 8 parameters, so the description must carry the load; it only adds 'Use ISO country and currency codes', which largely restates the ^[A-Z]{2}$/^[A-Z]{3}$ patterns. The order of parameter names in the first sentence adds no meaning beyond the keys themselves, and real ambiguities go unaddressed — notably that 'subscriptions' appears in both the billing_model and business_category enums, and the 'notes' field is never mentioned.

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 opens with a specific verb ('Compare') and enumerates exactly which inputs are matched against the PayFresco capability catalog, so the resource and operation are unmistakable. It does not, however, differentiate itself from the closely related sibling check_eligibility or application_readiness, which an agent would likely weigh against this tool.

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?

Clear exclusions state that it does not approve a merchant, quote a fee, submit an application, or contact anyone, which implicitly routes the agent to application_handoff/start_application for those needs. There is no positive statement of when to choose this over check_eligibility or application_readiness, so it stops short of full when/when-not guidance.

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