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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the description does not need to repeat them. It adds genuinely new behavior: a $0.005 charge, x402 payment requirements in the response, the no-charge-on-error rule, and venue reachability caveats (Binance/Bybit 'when reachable'). It stops short of describing rate limits or latency.

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?

Densely front-loaded: price, scope, normalization, then edge cases, then sample link. Nearly every clause carries information, though the $0.005 price is stated twice (title and first clause) and the x402 mechanics could be tighter.

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?

With two parameters, no output schema and a pointer to a sample endpoint, the definition is mostly sufficient for correct invocation. However, it omits the shape of the actual returned data (only 'x402 requirements + URL' is mentioned), so an agent cannot tell what payload arrives after payment.

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 50%: symbols is documented ('Optional; default watchlist') while venues has no description. The description partly compensates by explaining venue reachability and the minimum-venue constraint, but it never says what the default watchlist contains or how the venues array defaults when omitted.

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 verb+resource: 'cross-venue funding carry for 1-20 symbols', naming the venues and defining the spread as max-min. It is distinguishable from sibling tools like get_funding_history or get_extreme_funding, though it never names them explicitly, so sibling differentiation 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?

Gives useful context on the error path ('<2 venues or bad params return an error and no charge') and a free sample URL, but never states when to prefer this over get_extreme_funding, get_funding_history, or get_perps_context. The agent must infer selection from the purpose sentence alone.

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