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

Annotations cover read-only/idempotent/open-world safety, and the description adds the non-obvious commercial behavior: a $0.02 x402/USDC charge and that the call returns payment requirements unless payment_signature is supplied. That payment gating is exactly the kind of behavioral fact an agent cannot get from annotations or schema.

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?

Front-loads the purpose, then usage condition, then the cost/payment mechanics and sample path — every sentence carries distinct information with no filler.

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 explains the return behavior for the unpaid case (payment requirements) and the paid case, and all 8 params are optional and self-documented in the schema. It stops short of describing what a successful registry record contains or matching/limit behavior, a minor gap.

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 all 8 parameters documented, including LEI format, fuzzy name ranking, auto-detected query, and jurisdiction codes, so the baseline is 3. The description only touches payment_signature implicitly via the payment-flow sentence and adds no parameter 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?

Specific verb+resource with a clear scope: confirm a company exists, is active and is who it claims to be, backed by the title naming the registries (GLEIF LEI, UK, Norway). It does not explicitly distinguish itself from close siblings like counterparty_due_diligence, supplier_check, or sec_company_filings, so an agent must infer the boundary.

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 a clear use context — obtaining an official registry record for a counterparty before onboarding, invoicing or contracting. No explicit when-not or named alternative, so routing against sibling verification tools is left to inference.

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