get_subscription

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

No annotations are provided, so the description carries the transparency burden. It usefully discloses the API key prerequisite, the need to restart the server, and the fact that start_login will not unlock this tool. However, it does not state whether the call is read-only, what happens on missing/invalid credentials beyond setup, or what error/response behavior to expect.

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 compact and front-loaded: the first sentence states the purpose and return contents, and the second sentence provides essential access guidance. Every sentence earns its place with no filler or repetition of schema information.

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 zero-parameter read-style tool with no output schema, the description is reasonably complete: it names the returned subscription fields and explains the access setup needed. It could additionally describe failure modes or the exact response shape, but the essential calling context is present.

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 tool has zero parameters, so the baseline is 4. The schema is empty and the description correctly focuses on return content rather than parameter meaning. There is nothing more the description needs to explain about parameters.

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 gets current subscription details and enumerates the included fields: plan, status, billing period, and usage limits. It is specific about the resource and what is returned, though it does not explicitly differentiate itself from overlapping siblings such as get_usage or get_settings.

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 precondition: a Proof account is required, PROOF_API_KEY must be set, and the server must be restarted before calling again. It also warns that start_login does NOT open this tool, which is an explicit when-not. It does not name alternative sibling tools for similar subscription/usage data, stopping short of full alternative routing.

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