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

Beyond the annotations, it discloses auth and payment requirements: Coil Live subscription (7-day trial), connector sign-in, and x402 per-call payment. It also states the failure mode—without a subscription or x402 wallet, it returns a PaymentRequired object and no data—and notes the payload's `reading` field, adding rich behavioral context for invocation.

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 front-loads the core return content and then adds prerequisites and failure behavior. The sentence about the payload's `reading` field is somewhat cryptic and could be trimmed, but overall the length is justified by the auth and payment details.

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, the description carries the burden of explaining what is returned. It states the leadership states and references a `reading` field, and it covers access prerequisites and failure behavior. It does not fully describe the payload structure, but it is complete enough for an agent to decide to call it and understand the payment gate.

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 no parameter semantics to document. Per the rubric, a zero-parameter schema establishes a baseline of 4, and the description appropriately does not need to compensate.

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 states a specific resource and scope: 'X/SPY leadership states (GO / HOLDING / TURNING / OUT) for the 11 sector ETFs and every macro-book instrument,' recomputed intraday. It also explicitly labels itself the 'Live intraday version,' which distinguishes it from the sibling get_rotation without requiring the 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?

It clearly frames the context for use as the live intraday rotation read and explains the subscription/payment prerequisites. It does not explicitly name get_rotation as the non-live alternative or state when-not to use this tool, so it falls short of full alternative routing.

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