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

With no annotations, the description carries the full burden and does well: it discloses that nothing is spent, that quotes come from the Uniswap v4 Quoter on the deepest USDC pool, that a hook refusal or failed read is rejected before payment, and the $0.002/x402 cost and accepted chains. It stops short of describing output shape or any rate/coverage limits.

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 front-loaded with the core capability first and the payment mechanics later; no filler. Slightly dense with pricing/chain detail, but every clause conveys actionable information.

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?

Covers the gaps a 2-param, no-output-schema, no-annotation paid tool would otherwise leave: cost, read-only nature, failure handling, and the x402 handshake. It does not explicitly sketch the returned quote structure, which is a minor omission given there is no output schema.

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 baseline is 3, but the description adds real value over the schema by explaining the two-step `payment` protocol (fetch terms unsigned, then pass a signed payload) rather than merely restating the parameter. The `token` contract-address meaning is left entirely to the schema.

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 (quoting price impact) and resource (an Arc token), and pins the exact scope: buy and sell impact for $10/$100/$1,000 against the deepest USDC pool. An agent can distinguish this from arc_price / arc_price_at purely from the description, since it is explicitly a what-if, nothing-spent simulation with named amounts.

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 clear operational context and an explicit invocation sequence: call once without `payment` for terms, sign with your own wallet, call again with `payment`. It does not, however, say when to prefer this over arc_price or arc_price_at, so the alternative-selection guidance is missing.

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