trade_rail_quote

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

With no annotations present, the description carries the full burden and does so well: it discloses the refusal condition (unsellable token or round trip exceeding maxLossPct), that returned transactions are UNSIGNED and that nothing is signed, held or sent by the service, plus per-call cost and payment rails. This is exactly the behavioral context an agent needs before invoking a trade-adjacent tool.

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 description is dense and front-loaded with the core action, then the safety rule, then outputs, then payment mechanics. It is long but nearly every clause is load-bearing; minor branding ('APEX Trade Rail:') is the only filler.

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 7-parameter tool with no output schema, the description supplies what is missing: it describes the response contents (real pool, expected and minimum out, unsigned transactions), the refusal behavior, and the payment handshake. Nothing essential to correct invocation is absent.

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 meaning: it explains that maxLossPct caps the round-trip cost (0.5–15, default 15) and that `payment` is a signed x402 payload whose presence completes the purchase inside the call. That is more than a restatement of 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?

The description names a specific verb and scope: 'before a bot buys a token on Arc, X1 or BNB Chain, simulate the buy AND the sell back at its size.' This is a distinct pre-trade simulation/quote tool, readily separable from siblings like swap_build, exit_check or arc_token_check.

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?

It gives a clear trigger ('before a bot buys a token') and lays out the exact two-step x402 flow: call once without `payment` for the terms, sign, call again with `payment`. It does not name alternative sibling tools or state when NOT to use it, so it stops short of a 5.

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