update-subscription

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

Annotations declare destructiveHint: true, indicating a write operation. The description adds that the tool renews/extends expiry and specifies the key parameter. It does not detail side effects, permissions needed, or return value (no output schema). While consistent with annotations, it could provide more behavioral context.

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 moderately concise, with the key info front-loaded via a tip. It avoids redundancy but could be slightly shorter. Each sentence adds useful information, earning its 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 tool with a nested body schema and no output schema, the description covers the core action and key parameter. However, it omits what the response contains (e.g., updated subscription object or simple success). Given the complexity, more detail on expected output would improve completeness.

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 high (75%+), but the description adds value by highlighting the critical parameter: 'Body: { expirationDateTime (ISO 8601, new expiry) }'. This helps the agent focus on the main input needed for renewal, going beyond the schema's full property list.

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 tool's purpose: 'Renew a subscription by extending its expiry time.' It uses a specific verb-renew-and resource-subscription, and the tip reiterates. This distinguishes it from sibling tools like create-subscription, delete-subscription, and reauthorize-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?

The description advises calling 'before the current expirationDateTime to avoid missing notifications' and notes that max extension varies by resource type. It implicitly suggests only extending expiry, not modifying other fields. However, it does not explicitly state when not to use this tool or mention alternatives like reauthorize-subscription.

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