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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses capability limits ('cannot certify safety or detect every scam'), what is returned (cautious evidence score, risk flags, limitations), and cost/rate-limit terms ($0.005 USDC via x402 after 5 free calls/day). This is substantive behavioral context that annotations do not cover.

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 tightly packed sentences: use-case first, then return shape and limitations, then pricing. No filler, and the most decision-relevant information (when to use) is front-loaded.

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 values need not be detailed, and the description still summarizes them well while covering cost and capability limits. The remaining gap is the undocumented optional parameters, which leaves an agent guessing about wallet and amount inputs.

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 only 33% – only 'domain' is documented. The description says nothing about 'merchant_wallet_or_id' or 'transaction_amount_usd', leaving two of three parameters unexplained in both the schema and the description. It does not compensate for the coverage gap.

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 gives a specific verb and resource ('inspect public website evidence and missing trust signals') and a clear situational trigger (before purchasing from an unfamiliar merchant). However, it does not differentiate itself from the near-identical sibling x402_merchant_trust_check, which an agent cannot distinguish without opening both schemas.

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?

'Use before purchasing from an unfamiliar merchant' is a clear implied-use context, better than nothing. But it offers no exclusions, prerequisites, or named alternatives, and with a sibling of essentially the same name in scope, the routing guidance is incomplete.

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