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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds valuable context beyond annotations: 'the first eligible cached intelligence result is free; otherwise calls cost $0.001 USDC through x402' discloses cost and caching behavior. It also clarifies that output is 'event-probability data only,' which helps set expectations. No contradiction with annotations.

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 three sentences with no wasted words. The core purpose is front-loaded, followed by an important caveat and a concise payment note. Every sentence earns its place.

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 read-only tool with one optional parameter and no output schema, the description covers the essential operational details: what is read, the data type returned, the recommendation disclaimer, and the payment cost. It is slightly vague about what 'market context' includes, but the overall guidance is sufficient for an agent to invoke the 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 has 100% coverage for x_payment, explaining the signed payload and challenge/retry flow. The description adds complementary detail by revealing the payment cost and cached-result eligibility, giving the agent a clearer sense of when to expect charges. This exceeds the baseline for high schema coverage.

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 'Read' with a clear resource: 'high-volume open BTC, ETH, and crypto Polymarket markets with current outcome probabilities and market context.' It further narrows scope with 'Event-probability data only; not a recommendation,' and the crypto focus differentiates it from broader siblings like otto_pm_markets.

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?

Usage is implied rather than explicit: the description signals when to use the tool (for high-volume open BTC/ETH/crypto Polymarket markets) and provides a boundary ('not a recommendation'). However, it does not name alternatives or state when NOT to use this tool versus sibling tools like otto_pm_markets or otto_crypto_news.

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