ClockNext: subscribe customer to a plan

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

Annotations already indicate a non-read-only (readOnlyHint=false) and non-idempotent (idempotentHint=false) operation. The description adds behavioral context by explaining that the plan becomes active and that usage signals only price when an active plan's components match the meter. This goes beyond the annotations, though it doesn't discuss side effects like billing or return values.

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 two sentences, front-loaded with the core action, and includes both purpose and context without any redundant wording. Every clause adds value.

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 tool's complexity (6 params, 2 required), the schema fully documents parameters, and the description provides clear purpose, prerequisites, and a use case. The only gap is that no output schema exists and the description does not mention return values, but for a mutating subscription tool, this is a minor omission.

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 for parameters is 100%, meaning all six parameters have descriptions in the input schema. The description itself does not add parameter-specific semantics, but it does mention the concept of 'active plan' indirectly. Since the schema covers parameters thoroughly, the baseline of 3 is appropriate.

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 verb and resource: 'Subscribe a customer to a plan', and elaborates that this is a purchase that activates the plan. It distinguishes from sibling tools like clocknext_create_plan and clocknext_create_customer by specifying the action is about subscription/activation, not creation of entities.

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 gives explicit sequencing: 'do this after clocknext_create_customer + clocknext_create_plan' and a concrete use case: 'wire up a dummy customer before firing test signals'. However, it does not explicitly mention when not to use this tool or list alternative tools, which prevents a perfect score.

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