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

Adds substantial context beyond the readOnlyHint annotation: the $0.10 USDC cost, the required Solana mainnet payment, the challenge/response handshake, and the three-valued verdict plus evidence/sources in the result. These are behavioral facts an agent cannot infer from the 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?

Two dense sentences, front-loaded with purpose and outcome categories before the payment mechanics. The cost parenthetical is slightly awkwardly placed mid-sentence, but nothing is wasted.

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 compensates by naming the possible verdicts and stating that evidence and sources are returned, and it fully covers the payment prerequisite. An agent has everything needed 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 description coverage is 100%, so both parameters are already fully documented in the schema, including the example claim and the omit-then-retry payment flow. The description largely restates that flow, so baseline 3 is appropriate.

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 (verify) and resource (factual crypto-markets claim) plus the source of truth (sourced, dated claims cache), and enumerates the outcome space (confirmed/refuted/unverifiable). This clearly distinguishes it from the retrieval siblings get_price, get_metric, get_peg, etc.

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 operational guidance for the two-step payment flow: first call without payment_signature yields a challenge, then call again with the signature after paying. It does not name alternatives or state when-not-to-use, but for a paid verification endpoint the invocation context is unambiguous.

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