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

With no annotations, the description carries the full behavioral burden. It does add real value by disclosing the data source, liveness, and an x402 payment requirement ($0.02/call in USDC on eip155:8453). It does not say what happens for a non-stablecoin or unknown symbol, whether results are cached, or what error/empty behavior looks like.

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?

Front-loaded with the payload contents, followed by usage and pricing. Slightly redundant: "due-diligence read before an agent touches a stablecoin" and the following sentence both cover when to use it, but the text stays tight and every remaining sentence adds information.

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 compensates reasonably by listing the returned fields (peg price, depeg distance, supply, backing, chain breakdown) and the payment model. Gaps remain around unsupported symbols and response shape, but an agent has enough 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?

Only one parameter (symbol) with 100% schema description coverage and in-schema examples (USDC, USDT, DAI, USDS). The description implies the tool accepts "any stablecoin" but adds no syntax, format, or case-sensitivity detail beyond what the schema already provides, so the 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 resource (live stablecoin health) and enumerates the exact payload: peg price, depeg distance, circulating supply, backing type, and chain breakdown, plus the data source (DefiLlama). It is clearly distinguishable from the generic sibling crypto_price by scoping to stablecoins and peg-centric metrics.

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?

"The due-diligence read before an agent touches a stablecoin" and "Use this when an agent needs to peg, supply and chains" give a clear usage context. However, it never names the alternatives (e.g. crypto_price for general token prices, crypto_yield_pools for lending/supply yields), so routing between siblings is left to inference.

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