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

Goes well past the annotations (destructiveHint=true, openWorldHint=false) by disclosing data handling: the number goes to a secret store, only the last four digits are persisted and returned, and the caller should pass it once and never echo it back. That is exactly the privacy/sensitivity context an agent needs before calling a mutation tool on identity data.

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?

Three tight sentences, front-loaded with the action and the eligibility condition, followed by the prerequisite and then the sensitive-data handling rule. No filler, and the most important operational warning comes last where it is still prominent.

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, the description needn't explain return values, yet it helpfully notes the response only echoes the last four digits. Annotations cover the safety profile. The only gap is not naming the tool that records the document kind/country/expiry/state, which the agent must locate on its own.

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 67% and documentNumber has no schema description, but the description identifies what that parameter carries (a passport or driver's license number) with constraints implied by the source documents. The two ID parameters are only wrappers with schema descriptions, so the description's added value is mainly on the one undocumented parameter.

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 (files the document number for a beneficial owner) plus the exact scope: passport or US driver's license, on a banking application, for an owner with no SSN or ITIN. This cleanly separates it from the sibling banking_set_owner_tax_identifier, which covers the SSN/ITIN case.

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?

Gives a clear selection condition (owner has no SSN or ITIN) and a prerequisite sequence (record the document's kind, issuing country, expiry, and issuing state on the owner first). It does not name the alternative tool an agent should use when the owner does have an SSN/ITIN, so the routing is implied rather than explicit.

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