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

With no annotations, the description fully discloses that the tool is paid, the credit cost and pricing ranges, and that uncredentialed calls return a 402 payment envelope. It also specifies how to authenticate via X-API-KEY or x402 out-of-band, adding substantial behavioral context. It does not cover return format or rate limits, but the critical payment and auth behavior is well documented.

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 description opens with the core purpose, then details the computation, a parameter example, and a bracketed payment/auth section. While fairly dense and technical, the length is justified by the necessary paid-access details and the need to explain the data scope. It is reasonably front-loaded and every segment earns its place.

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?

Given the absence of both annotations and an output schema, the description effectively conveys the tool's data content, access requirements, and a parameter hint. It doesn't specify the response envelope or pagination, but the pointer to the 'instruments' tool for parameter docs and the 402 behavior cover the most critical operational aspects. Overall, it is adequately complete for a paid, single-endpoint scan.

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 schema defines no explicit properties (only additionalProperties) and defers parameter docs to the 'instruments' tool. The description adds a concrete '?city=nyc' parameter example, which provides meaning beyond the schema's generic string-based specification. With zero declared parameters, the baseline is 4, and the description adds valuable, though not exhaustive, 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?

The description clearly identifies the tool as a 'Polymarket monthly precipitation scan (5 cities)' and specifies the exact data computation involved (resolution-gauge floor, forecast distribution, bucket book comparisons). It narrowly targets precipitation, distinguishing it from general scan or other signal tools, though it lacks an explicit verb like 'get' or 'list'.

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 intended use is implied by the purpose and the '?city=nyc narrows' example, and the paid nature with cost details provides prerequisites. However, there is no explicit guidance on when to use this tool over alternatives like signal_stormy or signal_polymarket, nor any when-not-to-use criteria.

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