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

Annotations already cover read-only, idempotent, non-destructive, open-world. Beyond that, the description discloses real behavioral context: per-call cost of $0.08 USDC (or credits) and the exact auth mechanism — X-Payment / X-Payment-Tx / Authorization: Bearer fg_… in MCP headers, explicitly not in parameters. That is the kind of prerequisite disclosure the annotations cannot express. It doesn't cover failure/refund behavior on a failed paid call.

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 purpose is correctly front-loaded in the opening sentence, and the payment-header warning is placed last where it belongs. However, the parameter list is repeated three times ("参数 symbol 必填、quote 可选", "入参：symbol、quote", "Args: symbol, quote") and the field list is duplicated across the two languages, adding bulk without new information.

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 read-only lookup with no output schema, the description does the heavy lifting: it enumerates the returned data, states pricing and payment transport, and marks the required argument. What's missing is the semantics of quote and any note on response shape or failure handling for a paid call.

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%, so the description carries the full burden — yet it only restates that symbol is required and quote is optional, which the schema already enforces via required:[symbol] and default:null. It never explains what quote means (quote currency? default USDT?) or the expected symbol format. The meaning of the optional parameter remains undefined in both places.

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 first sentence gives a concrete framing — "which exchanges list this coin" — and enumerates the returned fields (per-exchange listing state, trading state, min order size, price precision, fees, listing timestamp, Binance last price). That makes the resource and depth unmistakable. It stops short of naming the sibling listing-status.listing_check or contrasting "full" vs "quick check", so the boundary is left 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?

Usage is only implied by the phrasing "Ask 'which exchanges list this coin' — full:" which signals this is the comprehensive variant. There is no explicit "use this when / don't use this when" and no named alternative among the listing-status siblings. An agent must infer the choice from how it was called.

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