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 substantial work: it discloses cost ($0.01 USDC on Base or Solana), that failed calls are not charged, that no account or API key is required, the upstream data source (DefiLlama), and the freshness claim ('Live'). It does not describe response shape or ordering beyond the field list, and there is no output schema, so the return contract is only partially covered.

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?

Four short sentences, front-loaded with the payment status and the core capability, with cost/access details following. No filler; the trailing raw URL is functional rather than wasteful, though it slightly clutters the flow.

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 full schema coverage, the description supplies what the schema cannot: payment, access model, data source, and the returned fields. The main residual gap is the shape of the response (row structure, whether chains are a field) which nothing else covers.

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%, with sort, limit, and min_tvl_usd each documenting allowed values and defaults. The description adds no parameter-level meaning (e.g., units, behavior of the min_tvl_usd default filter, or how sorting interacts with filtering), 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 resource and scope: live DeFi yield pools for the zest-v2 protocol across chains, returning APY, TVL, and 7d APY change from DefiLlama. The 'its pools across chains' phrasing implicitly distinguishes it from the chain- and token-scoped yield siblings, but it never names or points at 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 tool for zest-v2 protocol yields, and inclusion of the 'Paid' marker plus 'No account, no API key' tells it the access model. There is no explicit when-to-use/when-not guidance versus the many buy_yields_chain_* and buy_yields_token_* siblings, which is a real ambiguity for an agent selecting among hundreds of yield tools.

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