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

Goes well beyond the annotations by disclosing the fill mechanism (live OANDA streaming rate, buy at ask/sell at bid), the fallback (latest ECB reference rate when the pair is not carried), continuous paper fills, 160+ supported currencies, and the agent-key auth requirement. This is exactly the behavioral context the schema and hints cannot carry.

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?

Purpose and required inputs are front-loaded in the first clause, and the fill-mechanics sentence earns its place. The brace/pipe shorthand is dense but readable; no filler sentences.

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-parameter mutation tool with no output schema and a low-risk annotation profile, the description covers execution mechanics, auth, and the required inputs adequately. It is silent on the optional signal, competition, and dry_run behaviors, though the schema documents those at 86% coverage.

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 description coverage is 86%, so the schema already documents pair, qty, side, dry_run, and client_order_id. The description's pair-format and unit-of-base-currency details largely restate those schema descriptions rather than adding new semantics, so baseline 3 applies.

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 a specific verb+resource ('Paper-trade forex on YOUR agent book') and pins the three required inputs with accepted formats. It also distinguishes itself from the sibling order-placement tools by naming the asset class and by explicitly comparing its book/cash/guards to place_order.

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?

Usage context is clear: forex paper trades, agent key required, and the 'same book, cash and guards as place_order' note tells the agent this shares state with the general order tool rather than being a separate book. It never states when NOT to use it vs place_perp_order or place_order for a non-FX instrument, so it falls short of a 5.

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