Extend user subscription

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

Annotations only say readOnlyHint=false and destructiveHint=false. The description adds meaningful behavior: it explains the fallback to 'now' when no expiration or already passed, and that expired/limited users are moved back to active. This goes beyond annotations and helps the agent anticipate side effects.

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 dense sentences, no wasted words. The key nuance (relative addition, fallback to now, reactivation) is packed in early, and the alternative-handling sentence is a clear call-to-action.

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 mutating renewal tool with a true output schema, the description covers what happens to expiration, data limit, and status, and explicitly routes the agent away from the absolute-overwrite sibling. Nothing critical 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?

The description reinforces the schema's parameter docs by explaining addDuration is added to the current expiration, with fallback to now, and addData is added on top of the current limit. It also clarifies the relative rather than absolute nature. For username (the only undocumented param in schema), the description's 'renews a user' makes its role obvious.

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 ('Renews'), a resource ('a user'), and precisely what it does (adds duration and data). It names the sibling it is not (marzban_users_update) and contrasts relative vs absolute, so an agent can tell them apart.

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?

Explicitly instructs to use this instead of marzban_users_update for renewals, explaining the rationale (reads current expire/limit first so increment is relative). This gives clear selection criteria.

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