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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: the returned values are live (mark-price derived) and P&L is net of fees, plus the authentication prerequisite ("Requires an API key").

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?

A single tightly packed sentence with the resource and data content front-loaded. Nothing is wasted, though the auth caveat and the status clause are compressed into the same line rather than separated.

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 simple, safe read tool with a fully documented single parameter and no output schema, the description covers what is returned (positions with live mark price and net-of-fees P&L), how to filter, and the auth requirement. Only sibling differentiation is missing.

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% and the single enum parameter is self-documenting ("Omit for both"). The description clarifies that status="open" narrows to open positions only, which adds a little meaning over the schema, but it does not explain the closed case. Baseline 3 is appropriate.

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?

States the resource (paper positions) and even the payload contents (live mark price and P&L net of fees), which is more specific than a bare noun. It does not explicitly distinguish itself from close siblings like paper_orders or paper_trades, so an agent must infer the boundary from the noun alone.

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?

No when-to-use guidance and no named alternatives among the many paper_* siblings. The only routing hint is the filter behavior of status, which is a parameter concern rather than usage guidance.

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