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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description goes beyond this by detailing exact behaviors: walking the order ladder, returning verdicts, interpreting size_usd differently by mode, and warning that partial basket fills convert an arb into an unhedged directional position. This adds rich context without contradicting the 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 long but every sentence carries unique information required for correct use. It is front-loaded with the core purpose and uses capitals to highlight mandatory mode prerequisites. While dense, the structure mirrors the tool's complexity; a slight reduction in run-on phrasing would make it perfect.

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 must enumerate return values, and it does so for both modes: single-market returns top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, and verdict; basket returns theoretical_sum, realizable_sum, capture_ratio, profit_usd, per-leg details, thin_legs, and max_clean_notional_usd. It also covers edge cases like forced_directional_risk and clamping, making it complete for a tool of this complexity.

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 schema coverage is 100%, the description substantially enriches parameter understanding. For example, size_usd is explained as 'max spend on buys, target proceeds on sells' in single-market mode and as 'settlement notional' with shares-per-leg semantics in basket mode. It also clarifies defaults, clamps, and the auto-detection for basket side selection.

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-resource pairing: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It clearly distinguishes two modes (single-market vs basket) and explicitly references sibling tools (polymarket_arbitrage, polymarket_edges) to differentiate its role.

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 states when to use this tool: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also explains which mode to choose (market vs event) and why partial basket fills are dangerous, providing clear context for selection.

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