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

Annotations declare a non-readonly, non-destructive mutation; the description adds genuinely useful behavioral context beyond that: orders are virtual, no external exchange order is transmitted, and an agent key is required. It stops short of describing fill/persistence behavior, but the paper-trading nature is clearly disclosed and consistent with 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?

Three short, front-loaded sentences with the core purpose first. The phrasing is somewhat terse/awkward ('by design on YOUR agent book') but there is no filler and each sentence carries a scoping or safety fact.

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 7-param mutation tool with no output schema, the description covers purpose, safety, and auth, which is a reasonable core. However, it omits the role of meaningful optional params like the competition sub-book scoping and dry_run, leaving an agent without guidance on those capabilities.

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 57%; the three required params (coin, qty, side) have no schema descriptions, and the description only restates them (side buy|sell duplicates the enum) without adding units, format, or meaning. The optional params are documented in the schema, so the description does not need to carry them, but it fails to compensate for the undocumented required params.

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 specific verb+resource (place a virtual perp order on the agent's own book) and explicitly disambiguates from place_order by stating 'Not Alpaca equity trading.' An agent can tell it apart from the other place_* siblings, though the {coin, qty, side} restatement adds little beyond the schema.

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 establishes context ('virtual orderbook', 'no external perp order is sent', 'agent key required') which implies when it's used, but gives no explicit when-to-use/when-not guidance or prerequisites. It never mentions the dry_run preview path or when to scope to a competition, so selection between alternatives is left to inference.

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