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

Annotations (readOnlyHint, idempotentHint, openWorldHint) already establish the non-destructive, read-only nature. The description adds substantial behavioral detail beyond that: it walks the ladder, computes VWAP/slippage, returns a verdict (clean|degraded|cannot_fill), and in basket mode reports per-leg fill details and forced_directional_risk. This materially exceeds what annotations convey.

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 sentence earns its place for a two-mode tool with no output schema. It front-loads the core purpose, then systematically covers requirements, mode-specific behavior, return fields, and usage guidance. It could be improved with bullet points, but the density is justifiable given 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 must explain return values, and it does so comprehensively: top_of_book, vwap_fill_price, slippage_pp, shares_filled, max_fillable_usd, verdict; then for basket mode theoretical_sum vs realizable_sum, capture_ratio, profit_usd, thin_legs, max_clean_notional_usd, forced_directional_risk. It also covers prerequisites and failure modes, making it complete for a pre-trade risk-check 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 description coverage is 100%, so the baseline is 3. The description repeats the schema's parameter descriptions almost verbatim (e.g., side options, size_usd 'max spend on buys, target proceeds on sells'), adding no new per-parameter meaning. It does add the implicit one-of requirement for market/event, but that is more of a usage constraint than a semantic enrichment.

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 clear verb+resource: 'Realizable-vs-theoretical edge check against live CLOB order-book depth.' It further differentiates two modes (single-market vs basket) and explicitly names sibling tools (polymarket_arbitrage, polymarket_edges) to distinguish its role as a pre-trade validation step.

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 states 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, citing thin-book uncapturable overround and partial-fill directional risk, which gives clear context and an exclusion threshold.

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