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

Annotations already cover read-only, idempotent, open-world, non-destructive, so the bar is lower. The description still adds genuinely useful context beyond them: a free daily per-caller quota and the requirement to pass payment in X-Payment / X-Payment-Tx / Bearer headers rather than in arguments — a real failure mode for callers. It does not disclose pagination, quota exhaustion behavior, or result format.

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 hook and the payment-header warning are front-loaded and worth keeping. However, the content is duplicated across Chinese and English blocks and the '[zh]/[en]' scaffolding adds bulk without new information for most readers.

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-optional-parameter read-only scan, the definition covers purpose, tier limits, auth mechanism, and rough output shape (spread percent + grade), which is close to sufficient with no output schema available. The remaining gap is argument formatting for symbols and exchanges, which is squarely in the parameter dimension.

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% for both parameters, so the description must compensate and does not. It only repeats the names ('Args: symbols, exchanges') without stating format (comma-separated? array-as-string?), accepted exchange identifiers, or what happens when they are omitted (both default to null).

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 verb and resource: cross-exchange funding spread percent plus a signal grade, framed by the use case 'where is the funding rate arbitrage'. An agent can tell this is a scan/screener rather than a single-pair detail lookup, though it never names the sibling funding-spread.funding_detail to make the split explicit.

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 supplies an implied usage context (screening for arbitrage opportunities) and the quota note hints at a free trial tier. There is no statement of when to prefer this over funding_detail or arb-spread.spread_scan, nor any exclusion criteria.

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