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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond that: the x402 USDC/USDT on Base payment requirement, the no-signup model, and a 3-call free tier per wallet. It stops short of describing freshness guarantees or rate limits beyond the free tier.

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 tight sentences with zero waste: the capability and its slippage-adjusted qualifier lead, followed by venue scope and the payment model. Nothing is padded or repeated.

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 9-parameter, read-only, no-output-schema tool, the description covers the cost/auth model and what the result represents (spread and net edge). It could say more about the returned fields or quote freshness behavior, but the essentials for correct invocation are present.

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%, so the schema already documents all nine parameters including wallet, x_payment, and max_age_seconds. The description only loosely gestures at trade size ('given trade size') without adding format or interaction details beyond the schema. Baseline 3 applies.

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: a live cross-exchange crypto spread with slippage-adjusted net edge for a given trade size, scoped to major CEX venues. It is easily distinguishable from siblings like token_price or gas_fees, which do not compute cross-venue edge.

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?

Provides useful prerequisite context – pay-per-call via x402, no API key/signup, 3 free calls per wallet – but never states when to prefer this over token_price or how to interpret results vs. a simple quote. Usage is implied rather than contrasted with alternatives.

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