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

Annotations already cover read-only, idempotent, open-world, so the bar is lower, and the description still adds genuinely new behavioral facts: the call is paid, results are deterministic, and you get a single combined receipt rather than three responses. It does not say what happens if only one or none of the (all-optional) parameters is supplied.

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 tight sentences with the value proposition front-loaded. 'One call, one receipt' is slightly promotional but serves to convey the bundling benefit quickly, so almost nothing is wasted.

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 and annotations carry most of the load, but with zero required parameters the description should clarify whether a single identifier is a valid call or whether all three must be present to justify the paid invocation. Cost magnitude and partial-input behavior are left unstated.

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%, so the schema already documents all three parameters and their optionality. The description restates the same three identifiers without adding format, validation, or interaction rules, so 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?

Names the specific resource (a bundled supplier check over CNPJ + RFC + IBAN) and the verb (verify/check in one call). It is distinguishable from single-field siblings like cnpj_check and rfc_check because it explicitly frames itself as a combined pack, but it never names those siblings directly.

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?

'In one paid call' implies the use case is consolidating multiple single-country checks, but the description never states when to prefer this over cnpj_check + rfc_check + iban_check, nor when a sibling like vendor_onboarding_pack or africa_supplier_check is the better fit. Usage is implied rather than specified.

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