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

Beyond the annotations (idempotent, non-destructive), the description discloses the concrete defaults that apply when nothing is passed (live-price fills, no slippage, flat 0.5% maintenance margin), warns that the default diverges further from reality as position size grows, states the API-key requirement, and notes that open positions retain the margin they were filled with.

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?

Front-loaded with the purpose and defaults, then the write path, then the read path — logical order. The parenthetical venue-rate list is long but each value is decision-relevant; nothing else is padding.

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?

With no output schema, the description still tells the agent what a read returns (current setting, all venue rates, the full size-tier ladder) and covers the auth requirement, defaults, and persistence semantics, so nothing needed to call it correctly 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%, so the baseline is 3, and the description earns above that by adding information the schema lacks: the venue maintenance-margin rates behind each margin_venue value and the default slippage/ margin behavior that the booleans toggle away from.

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 states exactly what the tool governs — the realism of paper-trade fills and maintenance margin — and documents both modes (omit fields to read, pass fields to configure). Its scope is unique among siblings like paper_fees and paper_sltp, so there is no ambiguity about which tool an agent should reach for.

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 gives clear operative guidance: pass slippage and/or margin_tiers to turn realism on, pass margin_venue to adopt a named venue's rate, or omit every field to read. It never states when realism should *not* be enabled (e.g. when reproducing a default backtest), but the use context is otherwise unambiguous.

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