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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses the internal walk of the order-book ladder, the exact metrics returned (top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, verdict), and the risk of partial basket fills converting an arb into an unhedged directional position. This is deep behavioral context that the annotations cannot convey.

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 long but exceptionally well-structured, with clearly labeled SINGLE-MARKET and BASKET sections, explicit return lists, and a final 'USE THIS' guidance paragraph. Every sentence carries unique, decision-relevant information, and the key purpose is front-loaded in the first clause.

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?

Despite having no output schema, the description fully enumerates all return fields for both modes, describes the verdict values (clean|degraded|cannot_fill), and explains edge cases like forced_directional_risk and thin_legs. For a tool of this complexity, the description is complete enough for an agent to select, invoke, and interpret results correctly without external documentation.

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?

Although the schema already documents each parameter at 100% coverage, the description adds significant semantic meaning: it explains that `market` and `event` select mutually exclusive modes, clarifies that `side` has mode-specific defaults and basket auto-detection, and interprets `size_usd` differently for buys (max spend) vs sells (target proceeds) and for baskets (settlement notional per leg). This goes far beyond the schema's basic field descriptions.

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 opens with a specific, differentiated purpose: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It clearly distinguishes itself from sibling trading tools by focusing on fill risk, and it unambiguously describes both single-market and basket/partition modes with distinct verbs and resources.

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 guidance is explicit and actionable: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also explains why (theoretical overround on thin books is not capturable) and provides exclusions for partial fills and directional risk, leaving no ambiguity about when to prefer this tool over alternatives.

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