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 cost ($0.01 USDC), accepted payment chains (Base or Solana), the absence of account/API-key requirements, and the failure policy ('failed calls not charged'). It omits rate limits, pagination behavior, and error/response shape, which keeps it short of a 5.

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 the 'Paid.' qualifier and then packs purpose, data fields, price, payment options and failure policy into two dense sentences with no filler. The trailing endpoint URL is functional rather than redundant, though it slightly dilutes the tight core.

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?

A simple three-optional-parameter read with no output schema, and the description tells the agent what fields come back (APY, TVL, 7d change) plus the data source (DefiLlama) and the payment model. Enough to call it correctly; only pagination/rate-limit details are absent and they are minor here.

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 in the schema. The description adds no extra meaning about defaults, ranges, or how sorting interacts with the min_tvl filter, so the baseline of 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?

States a concrete verb and resource (live DeFi yields for the 3jane-lending protocol) and specifies exactly what the response contains — pools across chains with APY, TVL and 7d APY change. An agent can distinguish it from the hundreds of sibling buy_yields_protocol_* and buy_yields_chain_* tools because the protocol is named 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?

Usage is only implied by the name and the phrase 'its pools across chains'. There is no statement of when to prefer this over buy_yields_chain_*, buy_yields_token_*, or buy_yields_top, and no exclusions. The payment precondition ('$0.01 USDC on Base or Solana, no account, no API key') is scoping information rather than a when-to-use rule.

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