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

With no annotations, the description carries the full behavioral burden and covers the costly/operational facts well: pricing at $0.002 USDC per call, payment via x402 on Base, the FX rate source, and that the rate date is returned. It omits error/rate-limit behavior and how the premium is expressed (absolute vs percentage), which keeps it short of a 5.

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?

Three tight sentences: the operation and sources first, the default scope second, cost and payment last. Every clause earns its place with no 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?

For a single-optional-parameter read tool with no output schema, the description supplies the essential context: what is computed, from which sources, the default universe, and the cost. The remaining gap is the return shape — notably whether the premium is a percentage or a spread — which an agent would need to interpret results.

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 single symbols parameter (comma-separated, max 30, example tickers, omit-for-default) is already fully documented. The description restates the omit-for-default behavior but adds no new syntax or format detail, 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 a specific metric (Korea/kimchi premium per coin) and the exact data sources compared: Upbit and Bithumb KRW prices versus Binance USDT, converted via the ECB USD/KRW reference rate. This is unambiguous and clearly distinct from siblings like depth_slippage or macro_fx.

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 gives clear operating context: pass symbols to scope the query, omit them to get the top 20 Upbit markets by 24h KRW volume. However, it never states when to prefer this over adjacent siblings (depth_slippage, macro_fx, carry_pair) or any exclusions.

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