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

Annotations already declare destructive, idempotent and open-world behavior, so the bar is lower; the description still adds real value by disclosing the authorization gate and a per-call kill-switch/autonomy check. It does not explain what happens to partially filled orders or what the call returns, which keeps it below a 5.

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?

Two short sentences, front-loaded with the action and then the gating requirements, with no filler. The auth clause is dense jargon ('YOLO eligibility') that a reader may need to decode, which slightly undercuts clarity.

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 5-parameter destructive mutation with full schema coverage and rich annotations, the description covers action, selector and authorization gates. The remaining gap is outcome behavior — partial fills, failure modes, and whether anything is returned — which an agent would want before calling a destructive tool.

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 exchange, orderId, connectionId precedence and the market enum are already documented in the schema. The description only echoes the order-id selector and adds no new meaning about how pair or market affect routing.

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 gives a specific verb and resource ('Cancel an open CEX order') plus the key selector ('by order id'), which is enough to distinguish it from position-closing siblings like close_position. It stops short of naming an explicit alternative or clarifying the open-vs-filled boundary beyond the word 'open'.

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 prerequisites (trade:execute, YOLO eligibility, per-call kill-switch/autonomy check) but never says when to choose this over alternatives, nor points to list_open_orders for discovering an order id. Usage is implied by 'open order' rather than spelled out.

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