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

With no annotations at all, the description must explain behavior itself. It does disclose the core behavior — aggregating from multiple exchanges and producing best/worst/avg/spread metrics — which is useful. But it does not mention data freshness, latency, failure behavior, or that the operation is read-only, leaving significant behavioral gaps.

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?

The entire description is one dense sentence that packs in sources, assets, and output metrics without wasted words. The only flaw is starting with 'x402-price-screener:' which repeats the tool name, but this is a minor redundancy rather than a structural problem.

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?

The tool has no output schema and no annotations, so the description is the sole source of operational context. It does not explain the parameters' relationship, whether both can be provided, what happens if neither is provided, or the format of the returned aggregation. This makes confident invocation difficult despite the clear purpose.

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?

The input schema describes both parameters as 'to process', which is vague but counts as 100% coverage. The description adds helpful context by implying supported values (BTC/ETH/SOL), but it does not clarify the difference between 'coin' and 'symbol', whether either is required, or what value formats are expected. It provides some value beyond the schema but leaves key ambiguity.

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 states a specific function — multi-exchange price aggregation — with explicit resources (BTC/ETH/SOL), sources (coingecko, binance, kraken, coinbase), and computed outputs (best/worst/avg/spread). This clearly distinguishes it from sibling price tools like x402-crypto-price, x402-token-price, or x402-dex-price, even without naming them directly.

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 gives clear context for when the tool is appropriate: when a user needs cross-exchange aggregated prices for BTC/ETH/SOL rather than a single price quote. However, it does not explicitly state exclusions or name alternative tools, so it stops short of full when/when-not guidance.

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