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

Annotations already declare readOnlyHint, idempotentHint and closed-world, so the safety profile is covered. The description adds real value beyond that by naming the validation authority (Bankgirot checksum rules) and data source (official Bankinfrastruktur clearing table), and by enumerating the returned fields in the absence of an output schema.

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?

A single dense sentence that front-loads the primary action (validate) ahead of the secondary one (convert), with no redundant or filler clauses. Every phrase 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?

With no output schema, the description correctly compensates by listing the return fields (bank, BIC, account type, IBAN), and parameters are fully covered by the schema. What is still missing is failure behavior for an invalid account or unknown clearing number, which an agent would want before calling it.

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 all three parameters are already documented, including the optionality of 'number'. The description only echoes the clearing+account concept the schema already covers, adding no syntax, format, or validation detail of its own.

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 pair (validate + convert) on a specific resource (Swedish national bank account / IBAN) and names the mechanism (Bankgirot checksum rules, official Bankinfrastruktur clearing table). This distinguishes it from siblings like validate_iban and lookup_clearing_number, which only validate or only look up respectively.

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?

Usage is implied by the validate-and-convert framing, but there is no explicit when-to-use guidance or exclusion, e.g. whether to use this versus validate_iban or lookup_clearing_number first. The routing to alternatives is left entirely to the reader.

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