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

With no annotations supplied, the description carries the full burden and does well: it discloses that the call is paid, the exact price ($0.002 USDC), the accepted payment rails (Base or Solana), that no account or API key is needed, and that failed calls are not charged. That failure/payment policy is exactly the kind of non-obvious behavior an agent needs before spending money. It stops short of stating rate limits, pagination behavior, or result ordering beyond the sort 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?

Front-loaded with the 'Paid.' signal, then purpose, then cost and payment details, then the endpoint URL. Every sentence carries information an agent needs to decide and to pay. Slightly telegraphic — the pricing and URL tail could be tightened — but no wasted prose.

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-parameter read tool with no output schema, the description covers what is returned (pools, APY, TVL), the data source, the payment model, and the failure policy. The only material gap is that the response shape and row-level fields are unstated, which matters somewhat since no output schema exists.

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 in the schema. The description adds no additional parameter meaning — it does not explain how sort interacts with the returned APY/TVL fields or what happens when min_tvl_usd filters out most pools. 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 verb and resource: yield opportunities for the WEETH token, aggregated across protocols and chains, with APY and TVL sourced from DefiLlama. That scope cleanly separates it from the chain-scoped (buy_yields_chain_*) and protocol-scoped (buy_yields_protocol_*) siblings and from the other buy_yields_token_* entries, which differ only by asset.

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 WEETH' implies the use case, but there is no explicit when-to-use framing and no named alternative (e.g., use buy_yields_chain_base for a chain-wide view, or buy_yields_protocol_aave-v3 for a protocol-wide view). The agent must infer routing from the tool name alone.

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