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

Annotations already mark the tool read-only, idempotent, and non-destructive, and the description adds important behavior beyond that: the $0.005 USDC cost per x402 call, the unpaid call returning a payment challenge, and the rule that a call returning no data is never settled. It also clarifies that prices are probabilities in the 0-1 range.

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 dense but every sentence earns its place: returned fields, use case, probability semantics, payment behavior, and equivalent HTTP route. The most decision-relevant content is front-loaded, with payment/route details kept until the end.

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?

Since there is no output schema, the description compensates by enumerating the response fields directly: question, Gamma id, condition id, each outcome's USDC price and CLOB token id, best bid/ask, last trade price, volume, liquidity, and end date. It also covers sorting, closed-market behavior, and the payment/failure model, making the tool safe and correctly invokable without external documentation.

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 parameter details like limit range, allowed order values, and closed/ascending flags are already fully documented. The description adds only the high-level sort intent ('ordered by volume or liquidity') and does not provide extra per-parameter meaning beyond what the schema already gives.

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 verb and resource: 'List live Polymarket markets ordered by volume or liquidity,' and enumerates the returned fields. It also frames the tool's value as showing 'what the largest real-money prediction markets are pricing right now,' which distinguishes it from singular-market, event, and trade siblings.

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 a direct use case ('Use it to see what the largest real-money prediction markets are pricing right now') and clear context for market-wide listing and sorting. It does not explicitly contrast itself with siblings like polymarket_events, polymarket_market, or prediction_market_search, so the routing guidance is good but not complete.

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