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

Annotations already declare readOnlyHint=true, and the description adds rich behavioral context: 'walks the ladder,' returns slippage_pp, shares_filled, verdict values, per-leg fill detail, and 'forced_directional_risk naming the legs most likely to strand you unhedged.' It also warns about partial basket fills converting an arb into an unhedged directional position, which is a crucial safety disclosure beyond the read-only annotation.

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 earns its place. It is front-loaded with the core purpose, then uses uppercase labels (SINGLE-MARKET, BASKET, USE THIS) to organize distinct sections. Despite its length, it avoids redundancy and packs a large amount of essential information into a structured and readable format.

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 no output schema, the description thoroughly lists all returns for both modes (top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, verdict, theoretical_sum, realizable_sum, capture_ratio, profit_usd, thin_legs, etc.). It also explains edge cases like forced_directional_risk and the risk of partial fills, making it highly complete for a complex tool.

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 substantial meaning beyond the schema. It clarifies size_usd interpretation per mode: 'max spend on buys, target proceeds on sells' in single-market, and 'settlement notional S (shares per leg; each share pays $1)' in basket mode. It also explains the side default for basket mode (auto from partition sum), which is not in the schema.

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: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It clearly distinguishes from siblings by explicitly saying 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500,' which separates it from tools like polymarket_edges or polymarket_arbitrage.

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 provides explicit when-to-use guidance: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also explains the two modes (SINGLE-MARKET vs BASKET) and when each is appropriate, plus the risk rationale for partial fills and thin books.

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