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

Annotations already declare this a read-only, idempotent, closed-world operation, so the safety profile is covered. The description goes further by disclosing the fee model, the provenance of the fee data (Cantex measured, OneSwap/Tradecraft documented, others assumed at 1.5 CC), the extra CC/USDCx leg paid on via=usd routes, and the $0.50 net threshold for `clears`. Those assumptions materially affect how an agent should interpret results, which is real value beyond the 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?

Three sentences, all information-bearing, with the core definition front-loaded and fee semantics following. No filler or restatement of the name. The first sentence is dense to the point of being hard to parse on a single read, which keeps it from a 5.

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 burden of explaining return values, and it does define `cost_cc`, `swap_cost_cc` and `clears`. The fee-assumption caveat is exactly the kind of context needed to trust the numbers. It stops short of describing the full route payload (venues, sizes, prices) or ordering/pagination, leaving some gaps.

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 100% and the single `limit` parameter is fully documented in the schema ('best first, 1 to 50'), so the description need not repeat it. The description adds nothing about the parameter, which is acceptable at this coverage level. 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?

The description opens with a concrete definition of the resource: buy-on-one-venue, sell-on-the-other round trips after network fees. That distinguishes it from siblings like premiums, exit_cost and quote, which compute different quantities. It is slightly weakened by describing the output fields rather than stating a verb ('compute/list'), but the domain meaning is unmistakable.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative. An agent must infer from the wording that this is the arbitrage-opportunity tool rather than an exit-cost or quote tool. The `clears` threshold hints at a screening use case but does not state it as guidance.

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