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

No annotations are provided, so the description carries the full burden. It transparently discloses the cost ($0.02/call), the 404 behavior for untracked markets, the payment requirement, and the fact that charging only occurs on successful results. This is substantial behavioral context that goes beyond what the schema provides. It could be more explicit about rate limits or error handling, but the payment and cost transparency is excellent.

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 dense but well-structured: it front-loads the paid nature and core function, then details the data format and workflow. Every sentence adds critical information, and the payment flow is explained concisely but completely. No wasted words.

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?

Given the complexity of the payment workflow and lack of annotations, the description is remarkably complete. It explains the cost, the data format, the error case (404), the two-call payment process, and the charging behavior. There's no output schema, but the description explicitly defines the return format ([ts, yesUsd, noUsd]). This covers everything an agent needs to call 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?

Schema description coverage is 100%, so the schema already documents both parameters. However, the description adds critical meaning: it explains that marketId comes from predict_markets, and it details the exact format and usage of x402_payment (base64 X-PAYMENT payload). This adds value beyond the schema's basic descriptions, particularly for the payment workflow.

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 clearly states the tool fetches 24h odds history for a tracked Polymarket market, specifying the exact data format and sampling rate. It is distinct from siblings like predict_markets (which likely provides market metadata) and clearly describes its unique function.

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 explains when to use this tool (for historical odds data) and implicitly differentiates from siblings (e.g., predict_markets for other data). It also provides crucial usage instructions for the x402 payment workflow, including the two-call process. However, it doesn't explicitly mention when not to use it or name direct alternatives, but the payment flow guidance is strong.

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