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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds real behavioral context: the 402 check is a GET that never pays, hidden/unregistered sellers are excluded, results are ordered (record → outside payers in 30 days → host), and seller text is sanitized of price sentences and framed as data not instructions. That is substantial disclosure beyond what annotations provide, though the safety claim 'Read-only' at the end merely repeats readOnlyHint.

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?

A single run-on sentence chain riddled with nested parentheticals and semicolons ('approved by Priors, or under review with the facilitator's 402 check passed; never a hidden one'). The return-field list and the agent-offer carve-out are buried mid-paragraph rather than front-loaded, making it hard to scan.

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?

No output schema exists, and the description compensates by enumerating returned fields (address, per-endpoint price and answer time, last paid use, payment address, worker rate, Priors record) plus the ordering rule. Given the tool's complexity and the annotations covering safety, an agent has enough to call it correctly; only the query/limit behavior is under-explained.

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?

With 100% schema description coverage across both parameters (limit, query), the schema already carries full semantics. The description adds no interpretation of limit or query (e.g., how query matching interacts with the ordering), so baseline 3 applies.

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 ('List what an agent can pay over x402 in USDG on Robinhood Chain') with firm scope (chain 4663, USDG, facilitator-registered sellers). An agent can tell what it returns, but the definition never contrasts itself with near-siblings like find_services or find_agents, so differentiation is left to inference.

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?

Usage is implied through the inclusion rule and a downstream hint ('Pay one with pay_url from the agent's own @priors/mcp'), but there is no explicit when-to-use/when-not or naming of an alternative tool. An agent can infer this is the discovery step before paying, but must connect the dots itself.

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