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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description's real addition beyond structured data is the '(Cost: 10 credits)' disclosure, which is genuinely useful for invocation budgeting, but it says nothing about behavior on invalid/unknown codes or empty input, and an output schema already exists to describe 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 sentences, purpose front-loaded, ending with the cost tag. The only waste is the leading 'SWIFT Code Lookup:' label that merely restates the tool name and title before the real content begins.

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, open-world lookup with an output schema and fully documented parameters, the definition supplies what an agent needs: what fields it resolves, both input modes, and the credit cost. The remaining ambiguities (precedence between the two optional params, invalid-code behavior) are minor for this tool class.

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% and both parameters carry descriptions plus examples, so the schema already does the heavy lifting. The description marginally adds that the bank name path is a reverse lookup used to verify matching institutions, which clarifies intent beyond the bare 'name of the bank to lookup', but this is close to baseline value.

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 uses a specific verb and resource: it 'identifies the bank institution, branch, city, and country code behind any SWIFT or BIC code', and adds a second mode ('query by bank name'). That is clearly distinct from a generic lookup, but it never names or contrasts the nearest siblings (IFSCLookup, RoutingNumberLookup, IBANValidator), so the agent must infer which identifier system applies.

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?

'Search by code or query by bank name' implies the two usage modes but leaves the choice implicit — with zero required parameters, nothing states whether the agent must supply one, the other, or which wins when both are present. There is no guidance on when to reach for SWIFT codes versus the sibling IFSC/routing-number lookups.

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