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 real behavioral facts: stable URL semantics, auto-resolution/roll-forward, the added response fields, the HTTP endpoint, and the $0.02 x402 payment requirement. What is missing is the safety/side-effect profile (read-only, idempotent) and any rate or staleness limits.

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 mostly efficient, but the question text is duplicated verbatim across the first two sentences ('Will OPEC+ cut production at its next meeting?' appears twice), which is wasted space. The bracketed HTTP/price/docs metadata is useful but appended as a dense block.

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-arg, no-output-schema tool the description does the necessary work: it explains the evergreen lifecycle and names the two response fields (current_slug, rolls_to_next_at) that the schema cannot show. Payment terms are also given, leaving only pagination/rate details unstated.

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 (schema coverage 100%), so per the baseline a 4 applies. The description correctly implies no input is needed, though it adds nothing param-related, as expected for a no-arg tool.

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+resource ('Live probability') pinned to an exact, named question (OPEC+ production cut at next meeting), so an agent knows precisely what it returns. The 'stable evergreen URL for a recurring question' framing distinguishes it from the per-instance probability_get / probability_board_* siblings.

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?

'Auto-resolves to the current market instance and rolls forward on resolution, so the answer is always about the next occurrence' tells the agent when this tool is the right choice — when you want the recurring question rather than a fixed instance. It does not name a specific alternative or state exclusions, so it stops short of a 5.

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