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

Annotations only declare readOnlyHint and openWorldHint; the description adds the material behavior: pricing (0.002 USDC via x402), billing policy (400 before payment, no match or outage not charged), provenance (source named in every answer), and the register-vs-GLEIF routing. That is exactly the operational context annotations cannot carry.

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 use case, then search keys, source coverage, provenance, error/billing behavior, and price. Every clause carries distinct information; nothing is redundant with the schema or annotations despite the dense single-paragraph form.

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 multi-source, paid lookup tool, it covers inputs, coverage, provenance, and failure/billing behavior, which is close to complete. It never states the response shape beyond the field list, but it does say the source is named in every answer, leaving only minor gaps for an agent to call it correctly.

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%, so the baseline is 3, but the description adds real meaning by showing which key combinations are valid lookups (name with optional country, id, lei, or vat) and that GLEIF fills in for non-listed countries. It does not restate the id/VAT formats, which the schema already documents well.

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 and resource ('verify a company') plus the exact fields returned (legal name, address, legal form, status, LEI, register number, VAT validity). The lookup keys (name, id, lei, vat) make it unambiguous how the tool is driven, and the sibling tools (fx_rates, inflation, interest_rates, treasury_yields) are clearly a different domain.

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 concrete when-to-use contexts: KYC/KYB, supplier or invoice checks. It does not state when NOT to use it, but no plausible sibling alternative exists in the catalog, so the omission is low-risk. Coverage notes ('also firms without LEI') help the agent decide it is the right source.

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