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

Beyond annotations (readOnlyHint=true, idempotentHint=true), the description discloses detailed behavior: it walks the order-book ladder, returns a verdict (clean|degraded|cannot_fill), interprets size_usd differently for buys vs sells and basket mode, and warns about forced_directional_risk. It also explains the 'no user/workspace filtering' equivalent by noting the requirement for market/event scope. 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 every major section earns its place: mode requirements, parameter explanation, output list, and usage context. It uses clear uppercase labels (SINGLE-MARKET, BASKET, REQUIRES, USE THIS) for scannability. It could be slightly tighter in listing all return fields, but the detail is functional rather than wasteful.

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 fully carries the burden of explaining return values — and it does, enumerating top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, and verdict for single-market, plus theoretical_sum, realizable_sum, capture_ratio, profit_usd, per-leg fill detail, thin_legs[], and forced_directional_risk for basket. It covers prerequisites, parameter semantics, and failure modes, making it complete for a complex two-mode 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 crucial semantic detail not in the JSON schema. It explains that size_usd means different things in single-market mode (max spend on buys, target proceeds on sells) vs basket mode (settlement notional S = shares per leg). It also clarifies the side parameter's default behavior and the 'auto' mode for basket. This significantly enhances the bare parameter list.

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 precise verb-resource pair: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It distinguishes itself from sibling tools like polymarket_arbitrage and polymarket_edges by clearly framing this as a pre-trade risk validation. The two modes (single-market and basket) are explicitly defined, leaving no ambiguity about what the tool does.

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 gives 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 why (partial fills convert an arb into unhedged directional risk), giving strong contextual rationale. This directly names sibling tools and sets a threshold, making the decision process clear.

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