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

Alongside strong annotations (readOnly, openWorld, idempotent, non-destructive), the description adds valuable behavioral details: per-call cost, the x402 payment mechanism, the payment-challenge response for unpaid calls, and the no-data-no-settlement guarantee. This exceeds the annotations' coverage and helps the agent anticipate real call outcomes.

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 longer than average but remains dense and purposeful: it front-loads the tool's function, then the use case, then cost and failure behavior, then the HTTP route. Each sentence adds distinct value, though a slightly tighter wording could improve scannability.

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 carefully enumerates the response fields (title, slug, end date, volume, 24h volume, liquidity, open interest, market count, member markets), making the return shape understandable. It also covers cost, failure semantics, the no-data-cost guarantee, and the HTTP route, so an agent has everything needed to call and interpret this tool 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?

The input schema already describes all four parameters with 100% coverage, including defaults and ranges, so the description need not repeat them. The description does mention ordering by volume, which relates to the default sort behavior, but does not add further parameter-level meaning beyond the schema.

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 uses a specific verb ('List') and resource ('Polymarket events') and defines events as grouped questions such as an election or rate decision, distinguishing them from individual markets. It also enumerates the returned fields, making the tool's scope and output immediately clear.

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 explicitly says to use it when a question has many candidate outcomes and you want them together rather than one at a time, which gives clear context. It implies alternatives (individual market tools) but does not name them explicitly, and it omits explicit when-not-to-use guidance.

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