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 auto-resolve/roll-forward lifecycle, the added current_slug and rolls_to_next_at response fields, the HTTP method, and the $0.02 x402 cost plus docs link. It stops short of stating auth flow or rate limits, so not a 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?

Front-loaded and reasonably tight, but the question text 'Will Ethereum trade above $5k at year end?' is repeated verbatim in the first two sentences, which is pure waste. The trailing bracket block is dense but useful metadata.

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 zero-param, no-output-schema tool, the description covers the lifecycle behavior and the response delta ('standard probability shape' plus two named fields), which is enough for an agent to call and interpret it. Missing only auth/transport detail beyond the x402 price note.

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 tool takes zero parameters and the schema has 100% description coverage, so the baseline is 4. The description correctly adds no parameter guidance because there is nothing to parameterize.

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?

Names a specific verb ('Live probability') and a specific resource (Ethereum above $5k at year end), then explains the evergreen twist that separates it from market-instance siblings like probability_get or the probability_calendar_crypto family.

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 stated: 'recurring question' and 'always about the next occurrence' tell the agent this is for tracking a standing question, but no alternative (probability_get, probability_search) is named and no when-not condition is given.

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