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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context beyond that: it is explicitly 'informational triage only', costs $0.02 per call, returns a risk_score with scale (0 = safest), and includes flags like emi_issuer and no_vop. There is no contradiction with annotations.

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?

While longer than most, the description is tightly structured with labeled sections: USE WHEN, NOT, CHECKS, RETURNS, COST. Every sentence carries useful, non-redundant information. The purpose statement is front-loaded, and operational details like cost and output schema are clearly separated.

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?

Given the tool has a single required parameter, full schema coverage, and a rich output schema, the description still covers use cases, exclusions, alternatives, checks performed, returned fields, and cost. There is nothing an agent needs to call this tool correctly that is missing.

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?

There is only one parameter, iban, and the schema description 'IBAN to check' covers it 100%. The tool description adds context about what the tool does with the IBAN (compliance checks, risk scoring), but does not add new format or semantic detail about the parameter itself. Baseline 3 is appropriate given full schema coverage.

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 and resource: 'Run a full pre-flight compliance check on an IBAN before sending a SEPA / cross-border payment.' It clearly delineates the tool's function from siblings like validate_iban by enumerating the checks (sanctions, SEPA Instant reachability, VoP) and the returned compliance object. The purpose is unambiguous and distinct.

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?

The 'USE WHEN' block enumerates concrete trigger scenarios, including user phrasing like 'is this IBAN safe to pay?' and internal approval workflows. It also explicitly states when NOT to use it ('NOT A REGULATED AML/CFT PRODUCT') and names alternatives (Refinitiv, Acuris, ComplyAdvantage). This gives an agent explicit routing logic.

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