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

With no annotations, the description carries the full disclosure burden and does well: it states the tool is paid, the exact price and payment chains, that no account or API key is needed, and that failed calls are not charged. It omits rate limits, pagination, or response size, but the cost/auth/failure profile is unusually complete.

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?

Front-loads 'Paid.' then the data scope, then the payment terms in short declarative clauses with no filler. The raw URL at the end is the only arguably redundant element, since it duplicates transport-level configuration rather than helping tool selection.

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?

No output schema exists, and the description compensates by naming the returned metrics (APY, TVL, 7d APY change) and the upstream source. Combined with the zero-required-parameter schema, an agent has enough to call it and interpret results, with only formatting and pagination left unspecified.

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 coverage is 100%, with sort, limit, and min_tvl_usd documented inline including defaults and ranges, so the schema does the heavy lifting. The description adds no parameter guidance of its own, such as which sort to prefer when hunting high-APY pools, 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?

States a specific resource (live DeFi yields for the hastra protocol) and what each row contains: APY, TVL, and 7d APY change, from DefiLlama. The phrase 'its pools across chains' distinguishes it from chain-scoped siblings such as buy_yields_chain_*, though it never names those siblings 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?

Use is implied by the protocol name and the 'across chains' scope, and the payment requirements ($0.005 USDC on Base or Solana) set expectations before calling. But there is no explicit when-to-use or when-not guidance, no pointer to the chain-scoped or token-scoped yield tools as alternatives, and no note on what to do if the protocol is unknown or yields are missing.

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