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

With no annotations, the description carries the full burden and does well: it discloses the exact return fields (outcomes, implied probabilities, 24h volume, liquidity/open interest, end date, link), the ranking rule ('match then volume'), and a critical non-obvious trait — the $0.01 USDC per-call cost paid via x402 on Base. It omits error/failure behavior and whether the payment must be pre-authorized.

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?

Two sentences, both dense and front-loaded: the search scope and return shape come first, with the pricing constraint isolated and easy to spot. No filler clauses or redundant restatement of the tool name.

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?

For a 2-parameter tool with no output schema, the description compensates by enumerating the returned fields and the ranking order, and it surfaces the payment requirement. It stops short of explaining pagination behavior or what happens if the x402 payment fails, which is the main remaining gap.

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 both parameters are already fully documented in the schema with examples. The description only reinforces 'by keywords' for q and the ranking rule that motivates limit; it adds no syntax, format, or edge-case guidance beyond the structured fields. Baseline 3 applies.

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?

States a specific verb (search) and a precisely scoped resource ('open Polymarket and Kalshi markets'), so the agent knows exactly what corpus is queried. It does not, however, distinguish itself from sibling tools like odds_market or odds_top, leaving the selection decision partly to inference.

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 keyword-search framing and the 'open markets' qualifier imply when this tool applies, but there is no explicit statement of when to prefer it over odds_market (single market lookup) or odds_top (top markets). No exclusions or prerequisites are stated beyond the payment note.

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