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

Annotations already cover read-only/idempotent/no-destructive, so the bar is lower; the description adds versioning behavior and the fact that the payload itself signals when rules changed, plus the subscription/sign-in requirement. It does not describe payload size or caching/staleness characteristics.

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 resource and its content, followed by a compact second sentence covering versioning and access. The phrase 'engine-grade feed' and the run-on list are mildly wasteful but the text is short overall.

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 usefully enumerates what the rulebook contains and notes that change timing is embedded in the payload, which is enough for a zero-param read tool. Only the shape/format of the returned document remains unspecified.

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 of 4 applies; there is nothing for the description to disambiguate.

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 ('the Coil Live served rulebook') with a clear get semantic implied by the name, and enumerates the payload's subject matter (cycle order, exits-first, stop derivation, day-lane rhythm, sizing, fail-closed rules). It does not, however, distinguish itself from adjacent read tools such as get_engine_feed.

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?

Adds a real prerequisite: the caller must be a Coil Live subscriber with the connector connected and signed in, and the read only returns live data. But it names no alternative tool and gives no when-not condition, so the selection guidance is only implied.

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