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

With annotations already covering read-only/idempotent/non-destructive safety, the description adds substantial behavioral detail: it runs the same gate as the arb engine, performs contract identity checks, withdraw/deposit door checks, chain canonicalization, and strict unknown-support skipping. It also lists what the response contains.

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 front-loaded with the core purpose, then adds necessary gate details and return contents. It is dense and includes a redundant final parameter list, but most sentences earn their place for a complex check.

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?

Although there is no output schema, the description explains the return shape: viable, reason(s), per-chain doors, per-chain contract identity verdicts, and chosen route chain. Combined with full schema coverage and read-only annotations, this is complete enough for correct invocation.

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 input schema already documents base, buy_ex, and sell_ex, including their roles as buy/withdraw and sell/deposit venues. The description reinforces those roles in the executable path but adds no new parameter syntax or format beyond what the schema already provides.

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 states a specific verb and resource: it returns a cross-venue pair-gate verdict on whether BUY → transfer → SELL is executable. It clearly distinguishes this identity+mobility check from generic price or token-intel siblings by describing the exact gate semantics.

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 clear usage context: 'THE primary identity+mobility check before any cross-venue trade.' This tells the agent when to call it, though it does not explicitly name when not to use it or point to sibling alternatives.

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