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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds meaningful behavioral context beyond those annotations: it is versioned, updates on the next read when rules improve, requires a subscription with a 7-day trial, and requires connecting the Coil Live connector and signing in. It does not contradict any annotation.

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 is three sentences and front-loads the purpose before covering update behavior and subscription access. The first sentence is a dense list but every item is relevant to the rulebook's contents; the remaining sentences are brief and earn their 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?

For a zero-parameter, read-only tool with no output schema, the description covers what the rulebook contains, that it is live and versioned, and the subscription/sign-in requirement. It is largely complete, though it does not specify the return format or shape beyond describing the rulebook's topics.

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 has zero parameters and 100% schema description coverage, so there are no parameter semantics to explain. The description appropriately does not invent parameter details, matching the baseline for a no-parameter tool.

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 states the resource: the Coil Live rulebook, including its contents such as cycle order, exits, stop derivation, position sizing, day-lane rhythm, and fail-closed rules. It is a specific verb+resource definition, but it does not explicitly differentiate itself from the many sibling live/non-live tools, so it stops short of a 5.

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 description implies usage by calling it 'the fail-closed rules an agent trades against' and mentions subscription/sign-in prerequisites, but it never states when to call this tool versus alternatives or when not to call it. The usage context is inferable but not explicit.

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