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

No annotations exist, so the description carries the full burden, and it does well: it discloses the paid model ($0.002 USDC on Base or Solana), the no-account/no-API-key auth model, the failed-call-no-charge policy, and the upstream data source (DefiLlama). It stops short of rate limits, data freshness/latency, or how payment is actually settled, so it is strong but not exhaustive.

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 "Paid." then moves to purpose, then pricing, then auth guarantees — a sensible order with no filler sentences. The raw endpoint URL is arguably redundant for an MCP caller, a minor waste in an otherwise dense definition.

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?

With no output schema, no annotations, and three optional parameters, the description compensates by enumerating the returned fields (base/reward APY, TVL, 7d APY change) and the billing/auth model. Only the response shape details (units, ordering, row format) and pagination semantics are left unstated.

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 the schema already documents sort, limit, and min_tvl_usd with defaults. The description's "top pools by TVL or APY" echoes the sort parameter but adds no syntax, ordering tie-breaks, or interaction between limit and min_tvl_usd. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

"Live DeFi yields on Xlayer: top pools by TVL or APY" names the specific resource (yield pools), the chain scope (Xlayer), and the selection mode, which separates it from the many buy_yields_chain_* siblings for other chains and from buy_tvl_x-layer. An agent can identify the tool 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?

The description implies usage through context (live DeFi yields data, cheap paid call, no key needed) but never states when to prefer this over buy_tvl_x-layer or the buy_yields_protocol_* tools, nor any exclusion. With hundreds of near-identical siblings, an explicit routing sentence would have raised this score.

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