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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds genuinely useful scope disclosure: it is a structural/country-code check only and does not assert bank existence, live routing, or beneficiary identity. That is exactly the kind of limitation an agent needs before treating a pass as meaningful, though it says nothing about error behavior or partial matches.

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 short sentences, front-loaded with the affirmative scope and immediately followed by the exclusion. Every clause earns its place and nothing is padded.

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?

An output schema exists, so return-value detail is unnecessary in the description, and the single parameter is fully documented in the schema. The description covers purpose and limits adequately; the only minor gap is the absence of any pointer to complementary tools for the capabilities it disclaims.

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% with a single required parameter, and the schema itself documents the 8-or-11-character format and tolerance for spaces/dashes. The description adds no syntax or format detail beyond that, 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 (check) and resource (SWIFT/BIC structure and country code), which is enough to separate it from sibling validators like iban_check, ifsc_check, and lei_check. It does not explicitly name those siblings or contrast scope with them, so it stops short of a 5.

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 defines the tool's boundary via negation ('does not establish bank existence, active routing or beneficiary identity'), which implies the appropriate use case for pre-validation. However, it gives no positive when-to-use framing and names no alternative tool for the cases it disclaims, leaving routing to inference.

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