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

Annotations are empty, so the description carries the full burden. It discloses that the response contains the status and expiry_date, but gives no information on permissions, behavior when no subscription exists, or error cases. Given no annotations and no output schema, more behavioral context was warranted.

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 short, but the @param/@return tags are embedded awkwardly inline rather than structured, reading like raw docstring remnants. It is front-loaded with the purpose, which is good, but the formatting is sloppy.

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 trivial one-parameter read tool this is close to adequate, but with no output schema the description should characterize the returned object more fully; 'containing the customer id in the values object' is a thin and somewhat confusing return description given the tool is supposedly about subscription status.

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 0% for the single parameter, so the description must compensate. It does clarify that customer_id is 'the customer's database id', which distinguishes it from wallet or account identifiers, but it offers no format or constraint detail beyond that.

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: 'Returns the customer's current subscription status including the expiry_date.' An agent can tell this is a read of subscription state. It does not, however, differentiate itself from siblings like paywall__customer_validate_subscription or paywall__customer_log_subscription, which are adjacent in scope.

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?

There is no explicit guidance on when to call this versus paywall__customer_validate_subscription (validation) or the log/payment history tools. Usage is only implied by the tool name and the word 'status', so an agent must infer the trigger conditions.

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