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

Annotations already cover readOnly, idempotent, openWorld and non-destructive, so the safety profile is handled. The description adds genuinely non-obvious behavior: a per-call charge of $0.1 USDC (or prepaid credits) and the requirement that payment headers (X-Payment / X-Payment-Tx / Bearer) travel in MCP request headers rather than parameters — exactly the kind of operational context an agent cannot get from annotations.

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 core purpose is front-loaded, but the body is heavily redundant: the ranking and scoring explanation is stated once in English and again in Chinese, and the payment/vendor block is duplicated verbatim in zh and en. The same facts are repeated three or four times, inflating a simple no-argument tool into a long bilingual block.

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?

There is no output schema, so the description carries the return-shape burden, and it does enumerate the fields returned (TVL, APY, 30d mean, IL risk, score components, pool links). Combined with the payment and header requirements, an agent has enough to invoke it correctly; only a note on result freshness or ordering ties would add more.

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 reinforces it by stating '入参：无 / Args: none', confirming the tool takes no arguments. It further clarifies that payment credentials are deliberately excluded from the parameter set, removing a likely source of invocation error.

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 resource and scope: the top 20 stablecoin pools ranked by a risk-adjusted smart score, with an enumerated payload (TVL, APY, 30d mean, IL risk, score components). The word 'full' plus the 'top 20' count implicitly separates it from the top5/top10_entry siblings, though it never names them outright.

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 opening question 'which stablecoin pool has the best risk adjusted yield' gives a concrete trigger scenario, and 'full: top 20' hints this is the exhaustive variant versus shorter siblings. However, there is no explicit when-not guidance and no sibling is named, so the agent must infer that top5/top10_entry exist for abbreviated answers.

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