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

With no annotations, the description carries the full burden and does well: it discloses that the call is paid ($0.005 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and the underlying data source. It omits response shape, pagination, and whether the charge is per-call regardless of result size, which keeps it short of a 5.

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 'Paid.' followed immediately by what the tool returns, then the commercial terms, then the endpoint. Dense but every clause carries information; the only mild redundancy is restating the URL already implied by the tool's service.

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?

There is no output schema, so the description must describe returns, and it does: pools across chains with APY, TVL, and 7d APY change from DefiLlama. Combined with full schema coverage on the three optional parameters and explicit payment/access terms, an agent has enough to call this correctly; only response shape and pagination behavior are unstated.

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 sort, limit, and min_tvl_usd are already documented in the schema. The description adds no parameter-level meaning (e.g., how sort interacts with min_tvl_usd filtering) and only describes output fields, 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 verb and resource: live DeFi yields for the 'ember' protocol, with the exact fields returned (APY, TVL, 7d APY change) and the data source (DefiLlama). The protocol-scoped name plus 'its pools across chains' distinguishes it from the buy_yields_chain_* and buy_yields_token_* siblings, though it never says so explicitly.

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 by the resource scope: an agent can infer this is for looking up one protocol's pools rather than a chain or token. There is no explicit when-to-use/when-not guidance and no named alternative for chain-level or token-level yield queries, so routing depends on the agent reading the sibling names.

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