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

With no annotations, the description does substantial behavioral work: it discloses the $0.01 USDC price, Base or Solana payment, lack of account/API-key requirements, failed-call billing policy, and live DefiLlama sourcing. It does not explicitly address read-only behavior, rate limits, or detailed error and result behavior.

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?

The short statements efficiently cover purpose, data provenance, price, payment networks, authentication, failure billing, and endpoint without filler. Leading with "Paid" also foregrounds the financial cost before the agent invokes the tool.

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?

For a simple lookup with three optional parameters, the definition supplies enough operational context to invoke it: scope, principal metrics, source, cost, payment options, authentication requirements, and failure charging. Explicit sibling routing and a brief result-shape overview would improve completeness, particularly because no output schema is supplied.

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%, and the schema documents the allowed values, ranges, and defaults for all three optional parameters. The description adds no further guidance about sort, limit, or min_tvl_usd, so the fully documented schema carries parameter semantics.

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 clearly identifies protocol-specific Ethena USDe yield pools across chains and names the APY, TVL, and 7-day APY-change data provided. The resource and scope are clear, but there is no explicit retrieval verb or direct differentiation from the token-, chain-, and general-yield siblings.

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 wording implies use when live, cross-chain yield data is needed specifically for the ethena-usde protocol. It does not explain when to prefer this over buy_yields_token_usde, buy_yields_chain_*, buy_yields_top, or buy_yields_stablecoins, nor does it provide explicit exclusions.

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