cancel_and_replace_order

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

The description adds meaningful context beyond the annotations: the warning '⚠️ This modifies an existing order' reinforces the destructiveHint, and it states atomicity, supported asset types (equity, option, crypto), and parameter mutual exclusivity. These are useful behavioral details not present in the annotations.

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 well-structured: a one-sentence purpose, a clear warning, a supported-assets line, and a compact Args list. Every element serves a purpose, and the front-loaded purpose ensures the agent immediately understands the tool's function.

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 complexity (9 parameters, no schema descriptions) and the presence of an output schema, the description is quite thorough. It covers all parameters, conditions, and constraints. It lacks explicit failure behavior (e.g., what if the original order cannot be cancelled), but the atomicity hint partially addresses this. Minor gap prevents a 5.

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 0%, so the description carries full responsibility for parameter explanation. The Args section covers all 9 parameters with enums (order_type), defaults (time_in_force), mutual exclusivity (quantity vs amount), conditional requirements (expiration_time when GTD), and context (account_id optional if env var set). This fully compensates for the schema gap.

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 opens with 'Atomically cancel an existing order and replace it with new parameters,' which is a specific verb+resource statement that clearly distinguishes this tool from siblings like cancel_order and place_order. The atomicity qualifier adds valuable scope.

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?

While it doesn't explicitly mention alternatives like 'use this instead of cancel_order then place_order,' the phrase 'Atomically cancel an existing order and replace it' provides clear context for when this tool is appropriate. However, there are no explicit exclusions or when-not-to-use guidance.

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