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

Goes well beyond the annotations: it discloses that new stores can no longer subscribe while existing subscribers keep their approved terms, that an already-draft plan is returned unchanged (idempotency), and that the operation is reversible via `plan_activate`. This clarifies a mutation that annotations mark as non-destructive but which plainly has visible business impact.

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 core effect and sized appropriately for a mutating tool, with every behavioral sentence (existing subscribers, idempotency, reversal, return shape) earning its place. Minor redundancy in restating the parameter sourcing already present in the schema descriptions.

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?

Despite having no output schema, the description tells the agent the return value matches a single `plans_list` entry, and it covers the full behavior of the mutation including idempotency and reversal. Nothing needed to invoke this correctly is missing.

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 is 100%, so both required parameters are already documented, and the description largely repeats that sourcing (`plan_id` from `plans_list`, `app_id` from `apps_list`). It adds no meaning for `organization_id` and no format details beyond the schema, so the baseline of 3 applies.

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 verb and resource (take a Plan Builder plan off the pricing page by switching it to draft) and immediately names the sibling it inverts (`plan_activate`). The effect is concrete enough that an agent can distinguish this from `plan_update` or `plan_activate` without opening any 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?

Gives clear context for when this is the right call (removing a plan from the pricing page) and points to `plan_activate` for reversal. It does not explicitly exclude related alternatives such as `plan_update` for edits versus deactivation, so it falls just short of explicit when-not guidance.

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