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

With no annotations supplied, the description carries the disclosure burden and does so well: it states this is a paid call ($0.01 USDC on Base or Solana), that no account/API key is needed, and that failed calls are not charged — commercially important context an agent cannot get from the schema. It omits rate limits and payment-mechanism detail, so it falls short of full transparency.

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?

It is a single dense block with the most important qualifier ('Paid') front-loaded, followed by what is returned, cost, and access requirements. The trailing raw URL is arguably redundant with the tool name, but no sentence is filler.

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?

There is no output schema, yet the description enumerates the returned metrics (base/reward APY, TVL, 7d APY change), the pricing and payment rails, and the auth-free access model. For a read-only, three-optional-parameter paid endpoint, that covers everything an agent needs to decide and call correctly.

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%, and the parameters are already documented (sort by tvl/apy, limit 1-100, min_tvl_usd). The description only echoes the sort dimension and the returned metrics, adding no syntax, defaults, or edge-case meaning beyond the schema, 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?

The description names the specific resource (live DeFi yields), the chain (Arc), the ordering options (top pools by TVL or APY), and the exact fields returned (base/reward APY, TVL, 7d APY change, DefiLlama source). The explicit 'on Arc' scoping separates it from the many sibling buy_yields_chain_* tools for other chains.

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 Arc-chain yields tool from the text. There is no explicit when-to-use versus the protocol-level (buy_yields_protocol_*) or token-level (buy_yields_token_*) yield siblings, but the description does cover the prerequisite that no account or API key is required.

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