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

No annotations are provided, so the description carries the full burden, and it discloses the most important non-obvious trait: an MCP invocation does not return comparison results but payment requirements, which must be settled via an HTTP POST. That is exactly the kind of behavioral disclosure that prevents a failed call. It stops short of describing the returned comparison payload or error behavior, so 4 rather than 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?

Two sentences, front-loaded with the price and payment model, then the purpose, then the settlement mechanics. Every clause carries information an agent needs; there is no filler.

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 two-string paid tool with no output schema and no annotations, the description covers cost, payment flow, and the core operation, which is what an agent needs to avoid a dead-end call. The remaining gap is input format and expected result shape, which is real but secondary given no output schema exists to defer to.

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 0% for two required string parameters, so the description must compensate and largely does not. It restates the concepts ('Polymarket rules', 'bookmaker market description') but never says whether these are raw text, JSON, URLs, or how long/complex they may be. An agent knows what to pass conceptually but not in what form.

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 states a specific verb and resource: 'Compare Polymarket rules with a bookmaker market description.' That is far more concrete than the sibling tools (check_url, scrape_markdown, etc.), so an agent can tell this is a domain comparison task rather than a scraping task. It never says what the comparison produces (e.g., a mismatch report), which keeps it from a 5.

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 gives the essential context for deciding to invoke: the call costs $0.05 USDC on Base and, over MCP, will only return payment requirements rather than a result, with the settlement path spelled out (POST /v1/market-rules/compare with x402 headers). That is strong operational guidance. It does not state when not to use it or any prerequisite on input format, so it falls short of explicit alternatives/exclusions.

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