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

Annotations already indicate read-only, idempotent, open-world, non-destructive. The description adds depth by detailing that it 'walks the ladder,' returns specific fill metrics and a verdict, and warns about partial basket fills converting an arb into an unhedged directional position. There is 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 densely informative, structured into single-market and basket blocks with a clear usage call-out. Every sentence adds functional detail, and it is front-loaded with a one-line summary of the tool's core purpose.

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 compensates by listing all major return fields (top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, verdict) for single-market and a full set for basket mode (theoretical_sum, realizable_sum, capture_ratio, profit_usd, thin_legs, etc.). It also covers edge cases like thin books and forced directional risk, making it contextually 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?

All 4 parameters have schema descriptions (100% coverage), so baseline is 3. The tool description adds meaning by explaining dual interpretation of size_usd (spend on buys vs proceeds on sells vs settlement notional) and side default logic in basket mode, going beyond the schema. This extra context earns a 4.

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 'Realizable-vs-theoretical edge check against live CLOB order-book depth,' a specific verb+resource statement. It clearly distinguishes single-market and basket modes and lists distinct outputs for each, differentiating it from sibling arb/edge tools.

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 instructs 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500' and explains why theoretical overround is not capturable. It also contrasts single-market vs basket usage internally, providing clear when-to-use guidance.

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