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

Annotations already establish the safe read profile (readOnly, idempotent, non-destructive), so the description is free to add the substantive behavior: the exact gate logic run, the contract-identity rule (same ticker + different contract = separate assets), the door check per chain, and a 'strict unknown-support skip'. That is meaningful behavioral context beyond the annotations, though auth/rate-limit/error behavior is unstated.

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?

It is front-loaded with the core verdict question and keeps the gate details and return fields in a compact flow. It is dense and slightly long, but nearly every clause carries real information, so it stays efficient.

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 complex domain tool with no output schema, the description compensates by enumerating what is returned (viable, reason(s), per-chain doors, per-chain identity verdicts, chosen route chain). It leaves some edges (error/unknown-support handling detail) implicit, but an agent has enough to call and interpret it.

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% and the schema already documents base/buy_ex/sell_ex with examples and side semantics (withdraw/deposit). The description's closing 'Requires: base, buy_ex, sell_ex' merely restates the required list without adding format or constraint detail, so the 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 names a precise verb+resource (a cross-venue pair gate verdict) and frames it as a concrete question: is BUY → transfer → SELL executable for this token? It is instantly distinguishable from all siblings, which are data/agent/strategy tools with no overlap.

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 states a clear usage directive: 'THE primary identity+mobility check before any cross-venue trade.' That tells the agent when to reach for it. It does not name a specific alternative tool or any when-not-to-use condition, 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.