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

Annotations already state readOnlyHint=true and destructiveHint=false. The description adds significant behavioral context beyond that: it walks the order-book ladder, returns specific fields across modes, interprets size_usd differently (max spend vs target proceeds vs settlement notional), discloses that partial basket fills can strand the user unhedged, and notes the clamp range (10–1,000,000). It also clarifies that one of market/event is required even though the schema marks zero required, which is crucial operational transparency. 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 dense but every sentence earns its place. It is front-loaded with a one-line summary followed by REQUIRES, then clear sections for SINGLE-MARKET and BASKET, and ends with a usage directive. There is no fluff or redundancy; the length is justified by the tool's 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?

With no output schema, the description carries the full burden of explaining return values and behavior, and it does so thoroughly: it lists output fields per mode (e.g., top_of_book, vwap_fill_price, slippage_pp, theoretical_sum, realizable_sum, capture_ratio, thin_legs), explains the verdict values, and highlights the key risk of partial basket fills. It also covers parameter defaults and clamping. The tool's complexity is fully addressed.

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, but the description adds substantial meaning: it explains that market and event are mutually exclusive modes, defines side defaults and the 'auto' basket behavior, and clarifies size_usd semantics per mode (buys/spend vs sells/proceeds vs basket settlement notional). This goes well beyond the schema's property descriptions and enables correct invocation.

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 states a specific verb and resource: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It clearly distinguishes this tool from the sibling tools (polymarket_arbitrage, polymarket_edges) by framing it as a pre-trade risk check rather than a signal generator, and explicitly says 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.'

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 this tool vs alternatives: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also explains the context (theoretical overround on thin books is not capturable, partial fills convert arbs into unhedged directional positions) and differentiates the two modes (single-market vs basket), providing clear decision guidance.

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