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 goes well beyond these by disclosing the data source (SIX BankMaster, refreshed monthly), the breadth of payment-rail data, the exact return object structure, and the CH/LI-only applicability, all without contradicting the 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?

The description is well-structured with labeled sections (USE WHEN, BACKED BY, RETURNS, COST) and front-loads the core action. It is somewhat verbose due to promotional language and pricing details, but most sentences carry operational value for an agent deciding when to call the tool.

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 read-only lookup with a single required parameter and an output schema, the description is complete: it explains what is looked up, when to use it, what data backs it, what is returned, and the cost. No critical information is missing for 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?

Schema coverage is 100% with a clear type and description for the iid parameter. The tool description adds meaningful context by equating iid with BC-Nummer, specifying the 1-5 digit constraint, and giving concrete input scenarios like IBAN clearing codes and QR-IID resolution, helping the agent understand what value to pass.

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 a specific verb ('Resolve'), a resource ('Swiss BC-Nummer / IID'), and an outcome ('into the underlying institution'). It differentiates itself from sibling lookup_bic by emphasizing Swiss clearing data, payment-rail participation, and QR-IID resolution rather than a plain name/BIC lookup.

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' section explicitly enumerates trigger conditions including Swiss bank mention, CH/LI IBAN clearing codes, SIC/euroSIC routing, and QR-bill QR-IID resolution. The scope restriction 'Only relevant for CH and LI accounts' gives a clear exclusion, though it does not explicitly name a sibling alternative for non-Swiss lookups.

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