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

Annotations already mark the tool as readOnly, idempotent, and non-destructive. The description adds rich behavioral detail beyond that: it walks the CLOB order book ladder, returns specific fields (top_of_book, vwap_fill_price, slippage_pp, etc.), and for basket mode explains per-leg fill details, thin_legs identification, and forced directional risk. No contradiction with annotations.

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 relatively long but every sentence adds value. It is well-structured: first a one-sentence core purpose, then single-market mode details, then basket mode details, then usage guidance. It is front-loaded with the most important information. Could potentially be slightly shorter but appropriate given complexity.

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 the absence of an output schema, the description comprehensively lists all return fields for both modes (e.g., top_of_book, vwap_fill_price, verdict, per-leg fill details, thin_legs, max_clean_notional_usd, forced_directional_risk). It also explains the meaning of results (e.g., 'capture_ratio', 'profit_usd'). Given the tool's complexity, this is complete and actionable.

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?

Input schema coverage is 100%, but the description adds meaningful context: clarifies that size_usd means 'max spend on buys, target proceeds on sells' in single-market mode and 'settlement notional S (shares per leg)' in basket mode. It also explains the default side auto-detection in basket mode. These details enhance understanding beyond the schema 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 verb and resource: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It immediately distinguishes two modes (single-market and basket) and explicitly names sibling tools (polymarket_arbitrage, polymarket_edges) that this tool is meant to precede. The purpose is unambiguous and complete.

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 includes an explicit usage directive: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also warns when not to rely on theoretical edge (thin books, partial fills) and explains the specific risk of not using the tool (unhedged directional position). This is exemplary usage guidance.

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