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 cost ($0.005 USDC), accepted payment chains (Base or Solana), that no account or API key is needed, that failed calls are not charged, and the upstream data source. It still leaves the actual payment mechanics unstated, which matters for a pay-per-call tool.

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-loads the paid flag, then the resource, then pricing and access terms, then the endpoint. Dense but well ordered; the raw URL is the only element that feels tacked on rather than earned.

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 three-optional-parameter read tool with no output schema, the description covers what data comes back, its source, and the commercial terms. The remaining gap is how payment is actually settled at call time, which an agent invoking a paid endpoint would want spelled out.

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 with their defaults. The description adds no further meaning about filtering or sort behavior, so 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 and scope: live yield pools holding WBETH across protocols and chains, with APY and TVL from DefiLlama. It is clear what the tool returns, though it never explicitly contrasts itself with the many sibling buy_yields_token_* tools beyond the token name.

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 framing 'Where to earn yield on WBETH' implies the use case, and the paid/credential notes clarify access conditions. There is no explicit when-to-use or when-not-to-use guidance, and no routing to alternatives such as buy_yields_protocol_* or buy_yields_chain_* for users who want a different cut of the same data.

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