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 discloses that the call is paid ($0.005 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and where the data comes from. It omits rate limits, caching/freshness, and response envelope details, 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-loaded with the most decision-relevant word ('Paid') and packed into two tight sentences with no filler. The bare URL at the end is slightly noisy but plausibly useful for verification.

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 3-optional-parameter read tool with no annotations and no output schema, the description covers cost, payment rails, auth requirements, data source, and the fields returned. The remaining gap is the shape of the response (row count, pagination) and whether results are live or cached.

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 coverage is 100%, so sort, limit, and min_tvl_usd are already fully documented in the schema with defaults and ranges. The description adds nothing about parameter behavior, which is acceptable at baseline 3 but is a missed opportunity to note that min_tvl_usd filtering materially changes the pool set.

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 gives a specific verb and resource: live DeFi yield pools for the frax protocol across chains, with named data fields (APY, TVL, 7d APY change) and the upstream source (DefiLlama). It implicitly separates itself from the chain-scoped and token-scoped yield siblings, but never mentions the adjacent buy_yields_protocol_frax-ether sibling, which is a genuine ambiguity risk.

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: an agent can infer this is the tool for frax-protocol yields rather than a specific chain or token, but there is no explicit statement of when to pick it over buy_yields_chain_* or buy_yields_token_* tools. No exclusions or prerequisites beyond the payment terms are given.

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