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

With zero annotations the description carries the full burden and does well: it discloses the paid model, exact price, accepted payment chains, no-auth requirement, no-charge-on-failure policy, upstream data source, and the raw endpoint URL. It does not mention rate limits, caching/freshness, or response shape, but the core behavioral profile an agent needs before spending money is present.

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?

One compact block, front-loaded with the resource and result fields, followed by cost and access logistics. Every sentence carries information; the only minor blemish is the bare URL appended at the end without a label.

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?

There is no output schema, so the description must convey what comes back, and it does: per-pool rows across chains with APY, TVL, and 7d APY change. Combined with the fully described input schema and the payment terms, an agent has enough to decide and call correctly; only return formatting/pagination nuance is absent.

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 all carry defaults and allowed values in the schema. The description adds no meaning beyond that (e.g., what 'tvl' sorting produces or how chains are grouped), so baseline 3 is correct.

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 verb+resource: live DeFi yields for the hyperlend-pooled protocol, broken out by pool across chains, with the fields returned (APY, TVL, 7d APY change) and the data source (DefiLlama). The protocol-level scoping implicitly separates it from the buy_yields_chain_* and buy_yields_token_* siblings, but it never explicitly names an alternative.

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 context is implied by the protocol-specific name and the explicit paid-access terms ($0.002 USDC on Base or Solana, no account, no API key, failed calls not charged). However, there is no statement of when to prefer this over a chain-aggregate tool like buy_yields_chain_hyperliquid-l1 or a token-level tool, nor any exclusion guidance.

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