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

With no annotations, the description carries the burden and does well: it discloses the evergreen roll-forward semantics, the extra response fields (current_slug, rolls_to_next_at), and the payment/transport model (GET endpoint, $0.02 via x402). It does not cover auth requirements, rate limits, or staleness/latency.

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 core question and efficient overall, but the recurring question is restated verbatim twice ('Will Bitcoin trade above $100k at year end?') and the trailing HTTP/pricing/docs bracket is dense. Minor wasted repetition.

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 parameterless, read-only probability reader with no output schema, the description supplies the essentials: what it returns, how the evergreen roll-forward works, and the transport/pricing. Additional detail on the full 'standard probability shape' or freshness/latency would close the remaining 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 the baseline is 4. The description usefully adds that the response extends the 'standard probability shape' with current_slug and rolls_to_next_at, which is return-value context rather than parameter context.

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 ('Live probability') and a fully-specified resource ('Will Bitcoin trade above $100k at year end?'), which cleanly distinguishes it from siblings like probability_evergreen_eth-above-5k-eoy and probability_evergreen_sp500-positive-this-year. An agent can route here without opening any schema.

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?

The evergreen contract is explained explicitly: it auto-resolves to the current market instance and rolls forward on resolution, so the answer is always about the next occurrence. This tells the agent when this is preferable to a slug-specific probability_get, but it never names an alternative tool or states an exclusion.

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