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

Adds substantial context beyond the readOnly/openWorld annotations: an explicit price of $0.002 USDC per successful call, the x402 payment rails (Base, Solana, Arc), and the fact that failed calls are not charged. The cost model is the key behavioral fact for an agent deciding whether to call, and it is stated plainly.

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 short sentences: what it returns, what it does not return, and what it costs. Zero waste and the core purpose is front-loaded.

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?

An output schema exists, so return values need not be explained, and the description covers scope, symbol format, and billing. Only minor gaps remain, such as no mention of rate limits or whether the pair must be actively listed.

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% and the single parameter carries its own 'MEXC spot pair, e.g. BTCUSDT' description, so the schema does the work. The description repeats the same example without adding format rules or case sensitivity guidance, matching the baseline of 3.

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?

States a specific resource (MEXC spot last price for a single pair) and delimits scope with 'Last price only; no order book or history', which cleanly separates it from orderbook/history siblings. It does not distinguish itself from the many other exchange ticker siblings (binance, bitget, gemini, etc.) beyond the exchange name.

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 implied by the scope statement — call it when you need a single MEXC spot last price — and the exclusion of order book/history acts as a soft when-not. There is no explicit routing guidance to or away from the other exchange ticker tools.

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