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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint false. The description adds significant behavioral context beyond this: it explains that the tool walks the ladder, returns top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, and a verdict. It also highlights the danger of partial basket fills converting an arb into an unhedged directional position (the dominant loss mode). No contradictions 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 relatively long but well-structured with bold headings for modes and key terms. Every sentence earns its place by explaining mode-specific behavior, return fields, or usage guidance. It front-loads the purpose and provides detailed behavioral information. Could be slightly more concise without losing clarity, but overall efficient for the complexity.

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, many return fields, no output schema), the description is remarkably complete. It lists all return fields with clear explanations, details parameter behaviors for each mode, and warns about pitfalls like thin legs and forced directional risk. No gaps are apparent.

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%, so baseline is 3. The description adds substantial value beyond schema: it explains the dual meaning of `size_usd` (max spend for buys vs target proceeds for sells in single-market mode; settlement notional in basket mode), default values, and clamps. It also explains the `side` parameter's auto behavior in basket mode. 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 clearly states the tool's purpose: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It specifies two distinct modes (single-market and basket), lists the return fields, and explicitly differentiates from sibling tools by stating 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' This provides strong purpose clarity and sibling differentiation.

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 the tool: before acting on arbitrage signals or trades above $500. It explains the risk of partial basket fills leading to unhedged directional positions, which implies when not to use it (i.e., avoid converting an arb into a directional bet without checking). While it names alternative tools (arbitrage, edges) and positions this as a prerequisite, it does not provide exhaustive when-not examples. Nevertheless, the usage guidance is strong and context-rich.

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