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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, but the description goes far beyond: it details the walking of the order-book ladder, enumerates return fields (top_of_book, vwap_fill_price, slippage_pp, verdict, etc.), and explains the risk model (forced_directional_risk). This adds substantial behavioral context without contradicting 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 information-dense and well-structured: it opens with a one-sentence purpose, then uses SCREAMING CAPS for key requirements and mode demarcations. It lists return fields in each mode and ends with a usage directive. Every sentence earns its place; no redundancy or waffle.

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 it does: it enumerates the return fields for both single-market and basket modes, including verdicts, per-leg details, thin_legs, and max_clean_notional_usd. It also explains the risk of partial fills, making the tool's behavior fully predictable.

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?

While the schema has 100% parameter coverage with basic descriptions, the tool description enriches every parameter: it clarifies the mutual exclusivity of market/event, provides mode-specific side semantics (buy_yes/sell_yes default auto in basket), and explains size_usd interpretation (spend vs proceeds vs settlement notional). This goes well beyond the schema.

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 statement: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It clearly names the tool's function, scopes it to single-market and basket modes, and contrasts with sibling tools by explicitly referencing polymarket_arbitrage and polymarket_edges usage contexts. This uniquely identifies the tool's role.

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 specifies exactly when to use this tool: 'USE THIS before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500.' It also explains why (theoretical overround not capturable, partial fills convert arb to unhedged directional position), providing clear context and rationale versus alternatives.

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