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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds rich behavioral detail: it walks the order book ladder, computes VWAP fill and slippage, returns a verdict (clean|degraded|cannot_fill), and warns about partial basket fills becoming unhedged directional positions. This goes far beyond 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?

Although the description is long, every sentence contributes operational information or critical warnings. It is front-loaded with the core purpose, then methodically covers mode requirements, parameter semantics, return fields, and usage context. No filler or redundant restatement of the schema.

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?

There is no output schema, so the description must carry the full burden of explaining return values. It does this thoroughly 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, per-leg fill detail, thin_legs, max_clean_notional_usd, and forced_directional_risk. Given the tool's complexity, this is complete.

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%, so baseline is 3. However, the description provides substantial added meaning for every parameter: it defines single-market vs basket modes, explains the dual interpretation of size_usd (max spend on buys vs target proceeds on sells vs settlement notional in basket mode), and details the default behavior for `side` in basket mode. This significantly exceeds 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 phrase 'Realizable-vs-theoretical edge check against live CLOB order-book depth', clearly stating the tool's function and scope. It distinguishes itself from sibling tools like polymarket_arbitrage and polymarket_edges by framing this as the pre-trade fill-risk validation step.

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?

Explicit usage guidance is given: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' This clearly states when to use the tool, and the context explains why (theoretical overround on thin books is not capturable, partial fills convert arbs into unhedged positions).

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