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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the description's primary job is to add behavioral context beyond these. It does so by detailing the check process (walks the ladder, returns metrics like top_of_book, vwap_fill_price, slippage_pp, verdicts) and explicitly warns about thin books and directional risk. This adds significant value beyond the safety profile provided by 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 a single paragraph with clear section breaks (e.g., 'SINGLE-MARKET:', 'BASKET:') and uses bold for emphasis. It covers all necessary details without redundancy, though it is somewhat lengthy due to the tool's complexity. Every sentence adds value, and the structure is logical.

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?

Without an output schema, the description fully explains the return values for both modes (e.g., top_of_book, vwap_fill_price, slippage_pp for single-market; theoretical_sum, realizable_sum, capture_ratio, thin_legs for basket). It also addresses edge cases like forced_directional_risk, making the tool highly understandable for correct agent invocation.

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%, but the description adds meaning beyond the schema: it clarifies the dual mode (single-market vs basket), explains default side selection for basket, and elaborates on the interpretation of size_usd for both modes (spend vs target proceeds vs settlement notional) and the clamp range. This enriches parameter understanding.

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 specifies the tool's purpose: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It distinguishes between single-market and basket modes, and explicitly contrasts with sibling tools like polymarket_arbitrage and polymarket_edges by advising use before acting on their signals or trades 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?

Provides explicit when-to-use guidance: before acting on any polymarket_arbitrage SELL/BUY-EVERY-LEG signal or any polymarket_edges trade above ~$500. Warns about the risks of partial basket fills converting arb into unhedged directional positions, which clearly indicates when not to use or to proceed with caution.

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