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

With no annotations, the description does real work: it discloses the price ($0.01 USDC on Base or Solana), that no account or API key is needed, and that failed calls are not charged, which is the key billing-risk behavior an agent needs. It stops short of stating rate limits, latency, or whether the call is fully read-only/cached.

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?

Three tight clauses with the payload description front-loaded, followed by payment terms and URL. Every sentence carries information; the only minor cost is that the payment/commercial details are stacked densely and the endpoint URL consumes space.

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 paid tool with no annotations and no output schema, the description covers cost, auth, and failure charging, and it names the metrics returned (APY, TVL). It never describes the shape of a row (protocol, chain, pool, base/quote tokens), which matters when there is no output schema to inspect.

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% — sort, limit, and min_tvl_usd each carry their own description and defaults — so the schema does the heavy lifting. The description adds no meaning about sorting semantics or how filtering by min_tvl_usd affects results, so 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?

Specific verb+resource: 'Where to earn yield on USDT: live pools holding USDT across protocols and chains, APY and TVL' tells an agent exactly what dataset is returned and its source (DefiLlama). It is distinguishable from the chain/protocol siblings by the token-scoped framing, though it never names a sibling explicitly.

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?

The phrase 'Where to earn yield on USDT' implies the use case (comparing USDT yield opportunities), and the payment note sets the commercial precondition. However, there is no guidance on when to prefer the chain_* or protocol_* yield siblings instead, and no exclusions or prerequisites beyond payment.

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