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

With no annotations, the description carries the full burden and does disclose two real behavioral traits: the depeg flagging threshold (>50 bps) and the x402 pay-per-call cost of 0.002 USDC. It does not say how often the data refreshes, what the ordering/ranking rule is, or what happens on the 402 response beyond the schema's note.

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 compact sentences: what it returns, the alerting behavior, then the cost. Front-loaded with the payload and free of filler.

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 and no annotations, the description does the important work of listing the returned fields and the cost model, so an agent knows what to expect. Minor gaps remain around refresh cadence and the exact meaning/limits of the default result count.

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 50%: paymentProof is documented in the schema, but `limit` (default 15, max 50) is not explained anywhere. The description's phrase 'top stablecoins by circulating supply' implicitly conveys the ranking that limit truncates, which is modest added value but no explicit semantics for limit.

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?

Names a specific resource (top stablecoins by circulating supply) and enumerates the returned fields: price, deviation from peg in bps, 1d/7d/30d supply change, peg mechanism. No sibling tool covers stablecoin peg data, so an agent can route here unambiguously.

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 only implied by the content itself — an agent infers it is for peg/depeg monitoring. There is no explicit statement of when to use it, when not to, or any alternative, though the sibling list contains no overlapping tool.

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