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

Annotations already declare the tool as read-only, open-world, idempotent, and non-destructive. The description adds behavioral detail beyond that: it walks the order book ladder, returns fill quality verdicts (clean|degraded|cannot_fill), identifies thin legs, and warns about 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 long but dense with useful information. It is structured with clear sections for single-market and basket modes, and a usage note at the end. Every sentence adds value, but minor condensation could improve readability without losing content.

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, four parameters, no output schema), the description is exhaustive. It details all return fields, edge cases (thin_legs, forced_directional_risk), and the behavioral impact of partial fills. No output schema is needed because the description covers the return structure completely.

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 100%, but the description adds substantial meaning: it explains the dual-mode parameter interaction (market vs event), the default side logic for baskets (auto from partition sum), and the nuanced interpretation of size_usd (max spend on buys, target proceeds on sells in single-market; settlement notional shares per leg in basket). This goes well 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 explicitly states the tool's purpose: a realizable-vs-theoretical edge check against live order-book depth. It clearly distinguishes single-market and basket modes, and specifies the output elements (top_of_book, vwap_fill_price, slippage_pp, etc.), making it distinct from sibling tools like polymarket_arbitrage and polymarket_edges.

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 gives explicit guidance: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It explains why (theoretical overround not capturable on thin books, partial basket fills create unhedged positions), providing clear when-to-use and implied when-not-to-use context.

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