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

Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior. The description adds a small behavioral note that 'claims are limited to the named official sources', which provides some context, but it does not disclose auth, rate limits, response details, or other meaningful traits 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?

The description is very short, but it is not well-structured or useful: 'Paid x402 UK tool for gb.invoice.company.match.v1 (AVAILABLE)' is largely endpoint jargon and does not earn its place. It lacks a clear functional summary, so brevity here is under-specification rather than effective conciseness.

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?

Given the tool has nested objects, an output schema, and many closely related siblings, the description is severely inadequate. It fails to explain what the tool does, how it relates to invoice matching, or what limitations apply, leaving the agent to infer almost everything from the name and schema.

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 80%, so the input schema already documents most parameters. The description itself mentions no parameter meanings, but it does not need to compensate heavily because the schema covers the key fields like company_number, vat_number, and idempotency_key.

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 only says 'Paid x402 UK tool for gb.invoice.company.match.v1', which essentially restates the endpoint/name without a plain-language verb or resource. It never explicitly states that it matches an invoice to a company; 'Claims are limited' is vague and does not clarify the core purpose.

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?

There is no guidance on when to use this tool versus siblings like match_uk_business_payee or verify_uk_invoice_and_payee. The description mentions availability and paid status but not any trigger conditions, prerequisites, or alternatives.

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