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

Annotations already cover read-only, idempotent, open-world and non-destructive, so the safety profile is handled; the description adds genuinely new behavioral context: it is free, it has a daily per-caller quota, and payment/credentials go in MCP headers (X-Payment / X-Payment-Tx / Authorization: Bearer fg_…) rather than in arguments. That auth-channel detail is the kind of operational fact an agent would otherwise get wrong. It stops short of describing response shape or quota-exhaustion behavior.

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 same content is delivered three times — the opening English hook, a [zh] block, and an [en] block that restates the vendor asset name and 'free (daily per-caller quota)' already present in the first line. The bilingual duplication roughly doubles length without adding information; only the payment-header sentence is structurally unique.

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 zero-argument, free, read-only overview with no output schema, the description conveys what an agent gets (10-exchange list, tier, official fee stance, budget-reality snapshot), the cost model and the auth channel. What is missing is any indication of the response structure or what 'tier' and 'official fee stance' actually contain.

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?

With zero parameters the baseline is 4, and the description explicitly confirms 'Args: none' in both languages, consistent with the empty schema. Nothing further is required for an argument-free tool.

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 concrete framing ('which exchange is cheapest to list on') and a scope ('free: 10 exchanges, tier, official fee stance'), so an agent can tell this is a free high-level snapshot rather than a deep lookup. It does not explicitly name how it differs from siblings like listing_intel or listing_digest, only hinting at being the entry point ('look at this first').

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 rather than stated: the phrase aimed at project teams deciding before committing ('每个项目方决策前先看这个') suggests it should be consulted first, and 'free' plus the daily quota hints it is the low-cost starting point. No explicit when-not-to-use or named alternative (e.g., go to listing_intel for per-exchange detail) is given.

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