Cancel an order

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

The annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious context beyond them: no rule evaluation runs on a cancel, and a halted account still permits it. It stops short of stating what happens on an unknown or already-executed order.

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 with no filler, and the identifying scope ('by the clientOrderId') is front-loaded before the behavioral notes. Nothing redundant is included.

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 three-required-parameter tool with full schema descriptions, rich annotations, and no output schema, the description covers scope and the two most surprising behavioral facts. Only edge-case outcomes (already filled, unknown id) are left unaddressed, which is a minor gap.

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 all three parameters are documented in the schema and the baseline is 3. The description adds a little meaning by tying clientOrderId to the decision record ('the clientOrderId its decision carries'), but says nothing extra about symbol or tradingAccountId.

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 ('Cancel') and resource ('a resting order this agent placed') plus the key selector (clientOrderId). It scopes the tool to orders this agent owns, which implicitly separates it from propose_order and read-only siblings, though it never names an alternative explicitly.

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?

Usage is only implied: 'resting order' signals the precondition, and the description makes clear it targets an existing order rather than creating one. There is no explicit when-to-use vs when-not statement, and no guidance on what to do if the order is already filled or unknown.

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