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 key behavior: only active markets inside the horizon are returned, results are sorted by resolution date, and the probability is a blended value. It also surfaces the HTTP endpoint, the $0.01 x402 payment requirement, and a docs link — meaningful cost/access context. Pagination and result-size limits remain unstated.

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 purpose and efficiently sized. The first two sentences overlap heavily ("next N days" vs "resolving inside the horizon"), a minor redundancy, but the metadata bracket is compact and useful.

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?

With no output schema and no annotations, the description adequately conveys what a calendar call returns (soonest resolutions and their probabilities). It falls short on the category/segment override relationship, which is the one non-obvious aspect of invoking this tool correctly.

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?

Schema coverage is only 33% (just the segment field is documented). The description clarifies the days horizon semantics but says nothing about what category accepts, how segment "overrides category," or how the two interact — leaving the primary filtering parameters underspecified in both schema and prose.

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: active markets resolving within the next N days, sorted by resolution date, with blended probability. An agent can grasp the intent immediately, though it never names or distinguishes itself from the many sibling probability_calendar_<segment> variants that likely do the same thing pre-filtered.

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?

"An agent's event calendar: what settles soon and where it stands" implies when it is useful, but there is no explicit when-to-use vs. when-not, and no guidance on choosing this tool over probability_calendar_<segment> or probability_board_*. Usage is only implied.

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