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

Beyond the read-only/idempotent annotations, the description discloses non-obvious behavior: unpublished APY stays null rather than zero, each call costs $0.008 USDC on Base via x402, unpaid calls return a payment challenge, and no-data calls are not settled. No contradiction with 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?

Several dense sentences, front-loaded with functionality and returned fields before payment/settlement details. There is no filler; even the cost and HTTP-route notes are valuable for an expensive, pay-per-call API.

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?

With no output schema present, the description enumerates the key returned fields, explains null APY semantics, and discloses cost and settlement behavior. Combined with the 100% schema coverage and annotations, an agent has enough context to invoke and interpret the tool 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?

The input schema covers all six parameters at 100% with examples and defaults, so the baseline is 3. The description restates the filter concepts and adds 'ranked by APY,' but it does not carry additional parameter-level semantics beyond what the schema already provides.

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 an exact action ('Screen DefiLlama's yield-pool universe'), enumerates the filtering dimensions and returned fields, and closes with the user goal ('find where a given asset earns yield'). This clearly distinguishes it from sibling price, protocol, and chain tools.

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?

Gives a direct use case: 'Use it to find where a given asset earns yield.' It does not explicitly name alternatives or exclusion conditions, but the stated context is clear enough for an agent to choose this tool for yield-pool screening.

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