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

Annotations already provide readOnlyHint and openWorldHint, so safety is covered. The description adds meaningful context beyond annotations: the exact cost ($0.003 USDC per successful call), the payment rails (x402 on Base/Solana/Arc), and that failed calls are not charged. It still doesn't mention pagination, rate limits, or error conditions, keeping it short of a 5.

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?

Front-loaded with purpose, then a returned-fields list, then payment/logistics. Three sentences with little waste, though the 'Information only, not financial advice' disclaimer is boilerplate that displaces more useful routing guidance.

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?

An output schema exists, so return-value documentation is not required, yet the description nevertheless summarizes the payload. Combined with full schema coverage, annotations, and explicit cost/payment semantics, an agent has everything needed to invoke it correctly.

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% and both slug and id are documented in the schema itself. The description echoes 'by slug or numeric ID' but adds no format, precedence, or conflict-handling detail (e.g., what happens if both are supplied). Baseline 3 applies when the schema carries the parameter documentation.

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?

Starts with a specific verb+resource ('Fetches details for a single Polymarket event by slug or numeric ID') and enumerates the payload (markets, outcome tokens, prices, volume, liquidity, rules, dates). This clearly separates it from sibling discovery tools like pm_search and from narrower pm_* tools such as pm_orderbook or pm_trades.

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?

Usage is implied by 'single event by slug or numeric ID', so an agent can infer this is the detail-lookup tool rather than a list/search tool. However, it never explicitly states when to prefer this over pm_search, pm_resolved, or prediction_polymarket, nor that slug must be obtained elsewhere. No exclusions or prerequisites are given.

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