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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses latency (about 8 s typical, 15 s worst case, allow a 30 s timeout) and the payment model ($0.002 in USDC per successful call via x402, failed calls free). It also pre-empts a likely misinterpretation by stating that net change is a supply delta, not separate mint and burn events.

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?

Information is front-loaded: what it returns first, then how to call it, then the mint/burn caveat, then latency, then alternatives, then price. Every clause carries real decision value, though the latency-and-pricing tail is dense enough that the sentence could be tightened slightly.

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 an output schema present, return values need no explanation, and the description covers the things the schema and annotations cannot: cost, latency/timeout budget, the semantic caveat on net change, and sibling routing. Nothing an agent needs to call this correctly is missing.

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 schema already documents the comma-separated tickers, the cap of 10, and the default of the 10 largest. The description adds only example tickers (USDT, USDC), which is marginal incremental meaning, 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?

The description names a specific resource (stablecoin market cap, 1/7/30-day circulating change, peg price and depeg %) and its source (DefiLlama), so an agent knows exactly what data comes back. It is clearly differentiated from crypto_defillama_yields and crypto_defillama_tvl_oracle, which are named later in the text.

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 explicitly states the two calling modes — pass comma-separated symbols or leave the field empty for the 10 largest — and then routes the agent elsewhere for adjacent needs (yields for pool APY/TVL, tvl_oracle for a single protocol's TVL). No condition is left to inference.

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