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

With no annotations, the description carries the full burden and largely meets it: it discloses the auto-resolve/roll-forward behavior, names the extra response fields (current_slug, rolls_to_next_at), and surfaces cost/auth via the x402 price and endpoint. It stops short of describing the base probability shape or failure behavior, keeping it below 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 with the question and the key roll-forward behavior, and the HTTP/pricing metadata is cleanly bracketed. Minor waste from restating 'Who wins the next Super Bowl?' twice, which slightly blunts it.

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 tool with no annotations and no output schema, the description is nearly self-sufficient: it explains the evergreen semantics and the two added response fields, and it links docs for the rest of the probability shape. Slightly incomplete on the base return shape, but the docs pointer covers it.

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, so the baseline is 4. The description correctly implies no input is needed since the question is baked into the stable URL.

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 and resource ('Live probability: Who wins the next Super Bowl?') and identifies the scope as the next/upcoming occurrence. It clearly separates itself from non-evergreen siblings by naming the concrete market, though it does not distinguish itself from generic readers like probability_get or probability_search.

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?

Implies usage by explaining the URL is stable and always resolves to the next occurrence, which signals 'use for recurring questions.' However, it never states when to prefer this over probability_get, probability_search, or the sports probability_board tools, so the agent must infer the routing.

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