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 the price and payment rails ($0.01 USDC on Base or Solana), that no account or API key is needed, that failed calls are not charged, and the underlying data source (DefiLlama). It says nothing about result ordering guarantees or freshness beyond the sort parameter, which keeps it from 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 key facts — paywall flag, then what the tool returns, then cost, access model, billing policy, and endpoint URL. Dense with no filler, though the comma-spliced clauses make it slightly harder to scan than a bulleted layout would be.

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 tool, the description supplies enough to invoke it confidently and even names the two return dimensions (APY, TVL). It does not enumerate the returned pool fields, which would be the remaining gap given there is no 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% — sort (tvl/apy), limit (1-100, default 20), and min_tvl_usd (default 100000) are each documented inline. The description adds no meaning beyond the schema for these parameters, so the baseline of 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 outcome: live yield pools holding PYUSD across protocols and chains, with APY and TVL from DefiLlama. This clearly separates it from buy_stable_pyusd (token metadata) and from the many buy_yields_token_* siblings keyed to other assets. It does not, however, explicitly contrast itself with any sibling, so it stops short of a 5.

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 implied rather than stated: an agent looking for PYUSD yield opportunities can infer this is the right tool, and the leading 'Paid.' signals a cost barrier. There is no explicit when-to-use, when-not, or pointer to alternatives such as buy_yields_stablecoins or buy_yields_chain_* for a chain-first view.

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