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

Annotations already carry the safety profile (openWorldHint=true, destructiveHint=false, idempotentHint=true), so the bar is lower. The description usefully adds the per-call price ($0.01 USDC), which is genuine behavioral context for a paid tool, but says nothing about rate limits, auth, or what the response contains.

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?

A single front-loaded line with no filler; the data fields come first and the cost caveat is appended last. It is appropriately sized, though it is terse to the point of under-specification rather than efficiently concise.

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 two-parameter lookup tool with no output schema and no annotation-level parameter detail, the description leaves both inputs entirely unexplained. An agent knows the topic but not how to actually call it.

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 0% for both parameters (chain, protocol), so the description must compensate and does not. 'protocol info' refers to returned data, not to the protocol parameter's accepted format or values, and chain is never mentioned at all.

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 resource ('DeFi yield data') and enumerates the returned fields (APY, TVL, protocol info), so an agent can tell it apart from crypto-price or market-intel by topic. However, it uses a bare noun phrase with no verb (get/list/filter), leaving the operation type implicit.

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?

No when-to-use guidance, no exclusions, and no named alternatives among the many sibling data tools. The only auxiliary information is a cost note, which does not help an agent decide whether this is the right tool.

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