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

Annotations already declare destructiveHint=true and idempotentHint=true, yet the description adds real value beyond them: the customer retains the current period's credits, already-written invoices persist, and repeated cancels are harmless. It also discloses auth-scope and workspace-claim failure modes, which annotations cannot express.

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 core effect on renewal is front-loaded and each subsequent sentence addresses a distinct behavior (credits retained, invoices kept, idempotency, auth, workspace). The telegraphic "Early access." fragment and the run of prerequisite clauses read slightly clipped, but nothing is wasted.

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 one-parameter destructive mutation with full annotation coverage, the description covers side effects, idempotency, and failure conditions thoroughly. The only gap is that with no output schema, it does not indicate what a successful cancel returns.

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 description coverage is 100% for the single parameter, and the schema already points to list_credit_bundle_subscriptions as the id source. The description adds nothing about the subscription_id itself, so the baseline 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?

"Stop a customer's credit bundle subscription from renewing" is a specific verb plus resource with an explicit scope (renewal stops, not deletion of credits/invoices). That cleanly separates it from sibling tools like update_credit_bundle_plan and list_credit_bundle_subscriptions.

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 gives prerequisites and exclusions that select correct use: idempotent re-cancel is a no-op, Early-access status, billing-write credential required, and a claimed workspace is mandatory (403 otherwise). It does not name a sibling alternative for changing rather than cancelling the bundle, which keeps it below a 5.

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