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

With no annotations supplied, the description carries the full disclosure burden and does well: it states the data source (DefiLlama), the cost and payment chains ($0.002 USDC on Base or Solana), that no account or API key is needed, and that failed calls are not charged. The read-only nature is only implied by 'live pools ... APY and TVL' rather than stated, which keeps it from 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?

The lead token 'Paid.' front-loads the most decision-critical fact, followed by purpose, cost, terms, and endpoint. Every sentence carries distinct information with no 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 no-parameter-required read tool with no output schema, the description covers cost, auth, failure billing, data provenance, and the shape of the returned data (APY and TVL). Only the exact return structure and pagination behavior are left unspecified, a minor gap.

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 schema including defaults. The description adds nothing about these parameters, 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?

The description gives a specific verb-and-resource framing: 'Where to earn yield on BUSD0: live pools holding BUSD0 across protocols and chains, APY and TVL.' Combined with the token-specific tool name, an agent can distinguish this from buy_yields_protocol_* and buy_yields_chain_* siblings without opening the schema. It stops short of explicitly naming the sibling it is not, so it lands at 4 rather than 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 purpose statement and the pricing line, which lets an agent judge whether the call is worth $0.002. However, there is no explicit when-to-use versus when-not guidance and no routing to alternatives such as the protocol-level or chain-level yield tools that could also surface BUSD0 pools.

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