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

With no annotations supplied, the description carries the full burden and does well: it discloses the billing model (paid, exact price, two payment chains, "failed calls not charged"), that no auth is required, and the upstream data source (DefiLlama). It stops short of rate limits, pagination behavior, or what an error/no-data response looks like.

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 and the resource in the opening clause, then layers data fields, price, payment rails, and endpoint. Dense and purposeful, though the trailing URL and payment details make it read slightly like a pricing blurb rather than a tool contract.

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?

Three optional parameters, no nested objects, and no output schema — and the description compensates by naming the returned metrics (APY, TVL, 7d APY change) in place of a return schema, plus the payment and failure semantics. An agent has everything needed to decide, pay, and call correctly.

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 fully documented in the input schema. The description adds no parameter-level meaning — its mention of APY/TVL refers to returned fields, not to how sort or min_tvl_usd behave. Baseline 3 is appropriate.

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+resource ("Live DeFi yields for vvs-standard") and enumerates the returned metrics (APY, TVL, 7d APY change). The protocol-scoped framing clearly separates it from the chain_*, token_*, and stablecoins siblings in the same family.

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 description establishes that the call is paid, the price ($0.01 USDC on Base or Solana), and that no account or API key is needed, which effectively serves as a prerequisite checklist. However, it never says when to prefer this protocol-scoped tool over buy_yields_chain_base or buy_yields_token_*, and gives no exclusions or fallback guidance.

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