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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond that: the clearing table is dated 2026-10-16, checksum validation follows bank-specific rules, and the tool deliberately does not verify account existence — all material caveats for interpreting results.

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 dense sentences with zero filler. The primary conversion action is front-loaded, and the limitations sentence follows immediately; the clearing-table date earns its place by telling the agent how current the mapping is.

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 still enumerates what comes back (IBAN, BIC, bank identity, checksum result) and clearly states the boundary of the check. Nothing an agent needs to call and interpret this tool correctly 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?

Schema description coverage is 100%, so both parameters are already documented in the schema, including the 4-digit (5 for Swedbank 8xxx) clearing format. The description adds no syntax, format, or constraint detail beyond the schema, so the 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?

States a specific verb and resource (converts Swedish clearing + account number to IBAN/BIC) plus three additional capabilities: bank identification and checksum validation. An agent can distinguish it from siblings like iban_check or se_validate, which handle the reverse or broader validation concerns.

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 scope note 'does not check that the account exists' usefully bounds expectations, but the description never names an alternative tool or states the condition that should route an agent to iban_check or se_validate instead. Usage is implied rather than guided.

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