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 it well: it discloses the price ($0.005 USDC), accepted payment chains (Base or Solana), that no account or API key is needed, that failed calls are not charged, and the upstream data source (DefiLlama). These are exactly the facts an agent needs before committing to a paid call.

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?

Purpose is front-loaded in the first clause before the payment boilerplate, and every sentence carries information. The phrasing is telegraphic and list-like rather than flowing prose, but nothing is redundant.

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 zero-required-parameter query tool with no output schema, the description covers what the result contains (pools, APY, TVL) and the commercial terms. It stops short of describing the response shape or whether results are paginated beyond the limit parameter, which is the only meaningful 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% and each of the three optional parameters (sort, limit, min_tvl_usd) already documents its meaning and default. The description adds no parameter-level detail such as valid sort values or how min_tvl_usd interacts with results, 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 pools holding REUSD across protocols and chains, APY and TVL (DefiLlama data).' An agent can immediately tell this is the token-level yield lookup for REUSD, distinct from the protocol-level and chain-level siblings in the buy_yields_* 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?

Usage is implied by 'Where to earn yield on REUSD', which is enough to know the situation it serves, but there is no explicit routing guidance such as using buy_yields_protocol_* when the protocol is already known, or buy_yields_chain_* when the chain is known. No when-not-to-use condition is given.

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