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 ($0.01 USDC on Base or Solana), requires no account or API key, and that failed calls are not charged. It does not cover rate limits, response shape, or pagination, which keeps it from 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 by the data scope, then cost, auth, and failure policy. Dense and mostly waste-free, though the raw endpoint URL is of marginal use to an agent that already has the tool bound.

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?

Covers purpose, returned fields, pricing, payment rails, and billing-on-failure, which is what an agent needs before paying for a call. No output schema exists, so the field list in the description usefully compensates; only pagination and response envelope details are absent.

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 nothing about parameter behavior or interactions, which is acceptable at the baseline but no more.

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 yield-basis protocol, listing the fields returned (APY, TVL, 7d APY change) and the data source (DefiLlama). The protocol scope separates it from the many sibling buy_yields_protocol_* tools by name, but the description never explicitly contrasts itself with chain-level or token-level yield siblings, so it falls short of a 5.

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?

Implicit guidance only: an agent can infer this is the tool for protocol-level yield data for yield-basis. There is no explicit statement of when to prefer buy_yields_chain_* or buy_yields_token_* instead, and no prerequisites beyond the payment note.

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