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

Annotations already disclose readOnlyHint, idempotentHint, and destructiveHint, so the description needs only to add context. It adds pricing per call and mentions decomposition, but does not explain what the decomposition returns or how validation results are reported. 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?

Two concise sentences deliver the core purpose first and the cost second, with no filler or redundant restatement. Every sentence earns its place.

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?

For a simple read-only, one-parameter tool, the description plus schema is almost complete: the required input is fully documented and annotations cover safety. The only notable gap is the absence of an output schema and any description of the return shape, but this does not block correct invocation.

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?

The schema description covers 100% of the single parameter, including format, length, and examples. The description repeats this information without adding further semantic detail such as validation rules, country extraction, or error behavior, so it does not meaningfully extend the schema.

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 states the specific verb 'validate' and the resource 'BIC/SWIFT', and adds 'decomposition' as a secondary behavior. This is enough to distinguish it from sibling validators such as validate_iban or validate_isin based on the target code type.

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 description gives no guidance on when to use this tool versus alternatives, despite a large sibling family of validators. It does not mention exclusions, prerequisites, or preferred contexts, so the agent must infer usage from the tool name alone.

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