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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description goes well beyond that by disclosing data volatility ('DefiLlama's own estimates and changes often') and precise pricing/charging behavior ('$0.002 in USDC per successful call, paid with x402 ... failed calls are not charged'), which are critical operational details not present in annotations.

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?

The description is two sentences, front-loaded with the core purpose and data fields. The second sentence efficiently delivers two distinct pieces of high-value context: data reliability and payment terms. There is no filler or redundancy.

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 read-only yield query with a fully described schema and an output schema, the description covers what is returned, how it can be filtered and sorted, the volatile nature of the estimates, and the payment model. No critical information needed to call the tool correctly is missing.

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 coverage is 100%, and the schema itself documents all three parameters with examples and defaults. The description restates that results are filtered by chain or project and sorted by TVL, but adds no syntax or format details beyond what the schema already provides. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

The description states a specific resource (DeFi lending and liquidity pool yields from DefiLlama) and lists the fields returned (APY, base and reward APY, TVL), filtering options (chain or project), and sorting (by TVL). It is very clear about what the tool does. However, it does not distinguish itself from the sibling tool crypto_defillama_yields, which appears to cover the same data, 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?

Usage is implied by the data description—an agent can infer this is for yield/TVL queries. But there is no explicit guidance on when to use this versus alternatives like crypto_defillama_yields, crypto_aave_lending_markets, or finance_curve_finance_pools, and no exclusions or prerequisite conditions are given.

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