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

Beyond the readOnlyHint=false and openWorldHint annotations, it discloses a full cost model: $0.01 per call via x402 USDC or card key, first 25 free, failed calls free, and repeats are billed, which explains the idempotentHint=false. It also states the tool only reads or computes and changes nothing. That is exactly the billing behavior an agent needs to plan calls.

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 front-loaded: it defines the event concept first, then what is returned, then uses, then pricing. It is dense but nearly every clause adds information. The only redundancy is 'each call is charged, so repeats are not free', which repeats the price sentence.

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?

There is no output schema, so the description must explain the return contents, and it does: volume, liquidity, end date, tags, open-market count, and leading outcomes by price. It also covers cost and read-only behavior. The only minor gap is whether results are sorted strictly by 24-hour volume when a query is supplied.

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 coverage is 100%, so the schema already documents q, limit, the 1-10 range, and the default 5; the baseline is therefore 3. The description reinforces the default behavior ('without it the busiest events by 24h volume') and gives an example value, but it adds no 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 gives a concrete verb and resource: it returns the busiest open Polymarket events by 24-hour volume, or events matching a search, and it explains that an event is one question containing one or several markets. It also lists the fields returned: volume, liquidity, end date, tags, count of open markets, and five leading outcomes. That detail lets an agent tell this tool apart from sibling tools such as polymarket_markets, polymarket_orderbook, and polymarket_price_history.

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 states clear use cases: 'see who leads a multi-candidate market' and 'browse what is being traded now', plus a concrete example (q=president). It does not explicitly say when to use polymarket_markets or polymarket_orderbook instead, so the agent must infer the split between event discovery and market-level detail.

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