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

With no annotations, the description carries the burden and does add real behavioral context: cost of $0.002 USDC per call via x402 on Base and the omit-chain default of top 25 chains. It omits error handling for an invalid chain name and the size/latency of a 25-chain response, which for a paid call an agent would want to know.

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?

Two compact sentences, front-loaded with the output content and ending with the payment constraint. No padding or redundancy across clauses.

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, the description usefully previews the return payload (median APY, top 5 projects, pool counts) and discloses pricing and the default scope, which is most of what a caller needs. Missing only failure behavior and rough response shape for the 25-chain case.

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?

There is a single parameter with 100% schema description coverage, so baseline is 3. The description restates the omit-for-top-25 default rather than adding new semantics such as accepted chain-name format or casing, so it adds nothing beyond the schema.

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 a specific resource and scope: a per-chain DeFi yield overview with TVL-weighted median stablecoin APY plus top-5 projects by TVL and pool counts. That distinguishes it in kind from the pool-level siblings (defi_pool, defi_yields), though it never names an alternative outright.

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?

It states the two usage modes — pass one chain, or omit to get the top 25 — which implicitly tells the agent how to call it. But there is no explicit when-to-use guidance versus defi_yields/defi_pool, and no exclusion or prerequisite beyond the payment note.

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