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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, so the bar is lower; the description adds that validation is deterministic and that a signed XDR-1 receipt is returned, which is meaningful behavioral context for a compliance tool. It could say more about failure modes or what the receipt attests to, but it adds real value beyond 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?

Three tight sentences, front-loaded with the core action and the usage triggers. The all-caps 'CRITICAL B2B KYB CHECK' is slightly promotional but not wasteful, and every sentence contributes.

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 one-parameter, read-only, idempotent validation tool with an output schema and rich annotations, the description supplies purpose, standard, usage triggers, and return-format hint. Nothing needed to invoke it 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?

With a single parameter at 100% schema coverage, the baseline is 3; the schema already documents the 20-character LEI string. The description only reinforces the identifier standard (ISO 17442), adding marginal meaning beyond the schema.

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 (validates), a precise resource (Legal Entity Identifiers per ISO 17442), and the exact validation mechanism (ISO 7064 MOD-97-10 check digits). This clearly separates it from the many sibling checks (iban_check, gstin_check, vat_mod97_check) that validate other identifier standards.

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?

Gives explicit when-to-use triggers: before entering contracts, issuing contractor payments, or verifying corporate counterparties. It does not name an alternative or state when NOT to use it (e.g., versus batch_validate), so it stops short of full routing guidance.

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