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

With no annotations, the description carries the full burden and does substantial work: 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 that the data comes from DefiLlama. What it omits is the response shape, pagination, and any rate limits, 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-loads the paid status, then the resource and returned fields, then cost, access terms, and endpoint. It is dense and largely waste-free, though the trailing URL and payment details read as a list rather than flowing prose.

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 3-optional-parameter tool with no output schema and no annotations, the description covers the important gaps: it names the returned metrics, the data source, the cost, the payment chains, and the failure-charging policy. Only the response structure and pagination behavior remain 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%, and the schema already documents sort (tvl default or apy), limit (1-100, default 20), and min_tvl_usd (default 100000). The description adds no additional parameter meaning beyond that, so the baseline of 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 DeFi yields for the frankencoin protocol, its pools across chains, with the fields returned (APY, TVL, 7d APY change) and the data source (DefiLlama). This distinguishes it in practice from the sibling buy_yields_chain_* and buy_yields_token_* tools, though it never names those alternatives 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 only implied: an agent can infer this is the right tool when it wants protocol-level yields for frankencoin specifically. There is no explicit statement of when to prefer it over the chain- or token-scoped yield tools, and no stated prerequisites or exclusions.

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