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

With no annotations at all, the description carries the full burden, and it does disclose several behaviorally relevant traits: paid access at $0.005 USDC on Base or Solana, no account or API key required, failed calls not charged, and DefiLlama as the data source. It stops short of describing pagination, rate limits, or response envelope, which is the remaining gap.

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?

A single dense sentence-set with the paid/access constraints front-loaded right after the scope. The trailing raw URL is marginal filler, but nothing is redundant or buried.

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-param, no-annotation, no-output-schema tool, the description covers cost, access model, billing behavior, and the metrics returned, which is most of what an agent needs to call it correctly. It lacks explicit scope comparison to the many sibling yield tools, which is the main omission.

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 documented with defaults and ranges in the schema. The description adds no parameter-level meaning beyond listing which metrics are returned, 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?

The description names the exact resource ('Live DeFi yields for avant-avusd: its pools across chains') and enumerates the returned fields (APY, TVL, 7d APY change). The verb is implied rather than stated ('Live DeFi yields for...'), but an agent can still tell this apart from the chain- and token-scoped yield siblings.

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?

It gives no when-to-use guidance and never names an alternative. An agent cannot tell from the text whether to pick this over buy_yields_token_* or buy_yields_chain_* siblings, or when protocol-level aggregation is the right scope. Only the pricing note ('Paid... $0.005') implies a cost/benefit decision, which is not usage guidance.

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