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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is clear. The description adds no extra behavioral context such as return format, error conditions, or authorization requirements, making it minimally adequate with annotations.

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 a single concise sentence that is front-loaded with the verb and resource. No unnecessary words or repetitive information, earning the highest score.

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 simplicity (a get-by-ID with two well-documented parameters) and strong annotations, the description is complete enough. The agent can infer the return value (the subscription action) and understands the action is safe and non-destructive. No output schema is needed for such a straightforward retrieval.

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%, with both 'actionId' and 'subscriptionId' having descriptive text. The description's 'by ID' adds no additional parameter meaning beyond what the schema already provides, 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?

The description 'Get a subscription action by ID' clearly states the verb (Get) and resource (subscription action), with an explicit scope (by ID). It distinguishes from the sibling subscription_actions-list tool, which retrieves multiple actions.

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 implies use when a specific action ID is known, but it does not explicitly contrast with alternatives like subscription_actions-list or mention exclusions. Context is clear, but no direct when-not-to-use guidance is provided.

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