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

With no annotations, the description carries the full burden and does well: it declares the tool is paid, the exact price ($0.01 USDC on Base or Solana), that no account or API key is needed, and that failed calls are not charged. It omits rate limits, pagination behavior, and response shape, which are the remaining behavioral gaps for a paid endpoint.

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?

Dense and front-loaded: 'Paid.' first, then what the tool returns, then pricing and access terms. Telegraphic sentence fragments are efficient here, though the pricing/payment clauses could be tightened slightly.

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 zero-required-parameter, no-output-schema paid read endpoint, the definition supplies everything an agent needs to decide and act: what data comes back, the source, the cost, the accepted payment chains, and the endpoint URL. Return-format detail is not required in the absence of an output schema.

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 meaning beyond that (e.g. what 'apy' sorting does with low-TVL pools or how min_tvl_usd interacts with sorting), so the 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 and scope: live yield pools holding ONYC across protocols and chains, with APY and TVL from DefiLlama. The token-specific name plus the explicit content list lets an agent distinguish it from the hundreds of sibling buy_yields_token_* endpoints 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?

'Where to earn yield on ONYC' clearly frames the use case, and the token-specific naming implicitly routes the agent away from buy_yields_chain_* and buy_yields_protocol_* siblings. It does not, however, state any exclusion or alternative path (e.g. when to prefer a protocol or chain endpoint instead).

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