Get subscription info

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: this uses the same public, unauthenticated endpoint that client apps use, requires no username, and operates on a subscription token rather than an admin/session token. This enriches the agent's understanding beyond the 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?

Two sentences with no filler. The primary action and key constraint are front-loaded, and the sibling tool comparison is integrated naturally. Every sentence earns 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?

Given the tool's simplicity (one parameter), full schema coverage, output schema presence, read-only annotations, and explicit sibling differentiation, the description is complete. Nothing an agent needs to call this correctly is missing.

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%, so the schema already fully documents subscriptionToken, including its location in the URL and its distinction from admin tokens. The description reinforces that the token comes from a subscription URL, but adds no meaning beyond what the schema already provides; the baseline of 3 is appropriate when the schema carries the parameter documentation burden.

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 states a specific verb ('Reads'), a specific resource ('subscription status/usage/expiry'), and the required input ('token from a subscription URL'). It also explicitly differentiates itself from the sibling tool marzban_users_get, so an agent can select it correctly without ambiguity.

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 gives a clear use case: diagnosing a broken subscription link without needing the username. It also names the alternative tool and the condition for using it ('admin-side lookup by username, use marzban_users_get instead'), providing explicit when-to-use and when-not-to-use guidance.

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