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

Adds substantial behavior beyond the annotations: billing resumes, the customer is charged on the next billing date, the date is derived from the subscription interval when omitted, and shop automations may trigger email/SMS and webhooks. The prepaid-subscription failure mode is especially valuable for a destructive, open-world write.

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 'WRITE:' action label, then the business rule, then the parameter behavior and side effects. Every sentence carries information, though the trailing endpoint path is largely redundant with the schema parameters.

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?

Covers the operation's effect, failure mode, default parameter behavior, and side effects, which is sufficient for a 3-parameter write with no output schema. It stops short of saying what the call returns or how to confirm success, which would be the only remaining gap.

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 the baseline is 3, but the description adds real meaning for next_billing_date: it explains the default derivation from the subscription interval and that the customer is charged on that date. customer_id and subscription_id are left to the schema, which is acceptable given full coverage.

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 ('reactivate') and resource ('a paused or cancelled subscription') plus the effect ('billing resumes'), and labels it 'WRITE'. This is readily distinguishable from siblings like awtomic_pause_subscription or awtomic_cancel_customer_subscription.

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 a clear use condition (paused or cancelled subscription) and one explicit exclusion (a cancelled prepaid subscription cannot be reactivated). It does not name sibling tools as alternatives, but the applicability rule is unambiguous.

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