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

With no annotations, the description carries the full burden and does substantial work: it discloses that the call is paid, the exact price and payment chains ($0.002 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and the upstream data source (DefiLlama). It does not cover rate limits, caching or freshness of 'live' data, or pagination beyond the limit parameter.

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?

The description is front-loaded with 'Paid.', then the purpose, then the commercial and access terms, so nothing critical is buried. Every clause carries information (cost, payment chain, no auth, no charge on failure, source), though the trailing raw URL is more logistics than agent guidance.

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 the return shape, and it does so at a high level: pools, protocols, chains, APY and TVL. With only three optional parameters and full schema coverage, an agent has enough to call it correctly. What is missing is output format detail (field names, row structure) and freshness semantics for 'live' data.

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 fully documented in the schema. The description adds only indirect signal by naming APY and TVL as the returned metrics, which hints at the sort dimension but does not explain defaults or units beyond what the schema already provides. Baseline 3 is appropriate.

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 a specific resource and scope: 'live pools holding RSETH across protocols and chains, APY and TVL (DefiLlama data)'. That verb-plus-resource phrasing plus the token name clearly separates it from sibling tools such as buy_yields_chain_* and buy_yields_protocol_*, and an agent can identify the right tool without opening the schema.

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 implies usage by saying the result covers RSETH pools across protocols and chains, so an agent knows when this fits. However, it never states when NOT to use it or points to alternatives, such as buy_yields_chain_ethereum for chain-level discovery or buy_yields_protocol_aave-v3 for protocol-level discovery. The guidance is implied rather than explicit.

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