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

Annotations indicate readOnlyHint, openWorldHint, idempotentHint, and no destructive behavior. The description adds that the tool checks CLOB order book depth, walks the ladder, and returns fields like slippage, shares_filled, and verdicts. It discloses that partial basket fills lead to unhedged directional risk, which is beyond what annotations provide.

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 a single dense paragraph but well-structured with clear sections for single-market and basket modes. It is front-loaded with purpose and usage guidance. While every sentence adds value, it could be slightly more concise or structured, but it is still efficient.

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 tool's complexity (two modes, many return fields) and lack of output schema, the description covers return values comprehensively (top_of_book, vwap_fill_price, slippage, shares_filled, verdict, theoretical_sum, realizable_sum, capture_ratio, profit_usd, thin_legs, forced_directional_risk). It also explains key concepts like settlement notional and directional risk.

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%, but the description adds significant semantic value: it explains how 'size_usd' is interpreted differently for single-market vs basket mode, and the default logic for 'side' in basket mode. It also clarifies the requirement for either 'market' or 'event' parameter. This exceeds the baseline of 3.

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 clearly states the tool's purpose as a 'realizable-vs-theoretical edge check against live CLOB order-book depth'. It distinguishes between single-market and basket modes, and specifies when to use it (before acting on arbitrage signals or trades above ~$500). This clearly differentiates it from siblings.

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?

The description explicitly says 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500'. It explains the consequences of not using it (partial basket fills convert an arb into an unhedged directional position) and implicitly advises against using it for small trades.

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