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

With no annotations, the description carries the full burden and does disclose meaningful behavior: auto-resolution and roll-forward on resolution, two extra response fields (current_slug, rolls_to_next_at), and a paid endpoint ($0.02 via x402). It omits failure modes after resolution and any rate/latency characteristics, keeping it short of 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?

The driving question 'Will there be a US government shutdown this quarter?' is repeated verbatim in the first two sentences, which is redundant given the tool name already encodes the topic. The evergreen mechanics and the HTTP/pricing footer do earn their place, and the purpose is front-loaded.

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-parameter read tool with no output schema and no annotations, the description covers purpose, the roll-forward lifecycle, the two added response fields, and the payment requirement, plus a docs URL for the full probability shape. The 'standard probability shape' is only referenced, not described, but the link mitigates that gap.

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 there is nothing for the description to disambiguate beyond what the empty schema communicates; the baseline for a 0-param tool is 4.

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 resource and scope: a live probability for 'Will there be a US government shutdown this quarter?' The evergreen mechanism (auto-resolves to the current market instance) distinguishes it from the non-evergreen probability_get and the many probability_board_* siblings, though it never names an alternative directly.

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?

'Stable evergreen URL for a recurring question' and 'always about the next occurrence' imply when to reach for this over a point-in-time probability lookup, but no sibling is named and there is no explicit when-not-to-use guidance or comparison to probability_get / probability_board_politics-us.

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