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

Beyond the annotations (readOnly, openWorld, idempotent, non-destructive), the description discloses operational behavior: it walks the order book, returns specific fields (top_of_book, vwap_fill_price, slippage_pp, etc.), models depth-crossing cost, and explicitly states fees are NOT modelled (gross vs net). It also warns about forced_directional_risk and thin books, adding substantial behavioral context.

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 well-structured, with clear sections (SINGLE-MARKET, BASKET, fees note) and no redundant filler. It is front-loaded with the core purpose and then provides mode-specific details. While it could be trimmed slightly, the length is justified by the tool's complexity and the need to convey both modes and caveats.

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 must cover return values, which it does thoroughly (listing all fields for both modes). It also explains the fee implication and when the tool is applicable, making it complete for an agent to call correctly without needing to inspect schemas or other sources.

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?

The schema covers all 4 parameters, but the description adds meaning beyond that: it explains the difference between single-market and basket interpretation of size_usd (max spend vs settlement notional), the auto-selection for side in basket mode, and the format of market/event (slug or URL). This enriches the schema's bare 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 states a specific verb+resource ('Realizable-vs-theoretical edge check against live CLOB order-book depth') and clearly distinguishes between single-market and basket modes. It explicitly references sibling tools (polymarket_arbitrage, polymarket_edges) and tells the agent when to use this tool over them, making purpose unambiguous.

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?

It provides 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') and explains the rationale (theoretical overround not capturable, partial fills create unhedged positions). It also explains how to choose between single-market and basket modes based on input types.

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