preview_order

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

With no annotations, the description fully explains behavior: it uses IBKR's whatif, returns margin/commission/warnings, and does not send the order. Parameter usage is also detailed, covering side, size options, and limit_price requirement.

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 sentences: first states purpose, second explains parameters. Front-loaded, no extraneous information. Every word serves a purpose.

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?

Given the tool's complexity (5 parameters, no output schema), the description covers everything needed: what the tool does, when to use it, how to set parameters, and what it returns.

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?

The schema has 0% coverage, but the description compensates by explaining that side is 'BUY' or 'SELL', size can be cash_amount (USD) or quantity (shares), and limit_price is for LIMIT orders needing quantity. This adds crucial meaning beyond schema types.

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 clearly states the tool's purpose: 'Preview an order's impact (margin, estimated commission, warnings) WITHOUT sending it.' It specifies the action (preview), the resource (order impact), and distinguishes it from executing orders like buy/sell siblings.

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?

The description explicitly says 'before committing,' indicating when to use this tool. It does not list alternatives or exclusions, but the context of sibling tools (e.g., buy, sell) makes the usage clear.

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