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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It implies a read-only check but says nothing about authentication requirements, what happens if no subscription exists, rate limits, or the nature of the returned status.

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?

A single, front-loaded sentence that precisely states the tool's purpose. Every word earns its place and no unnecessary detail is included.

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?

The description is adequate for a simple read-only tool, but with no output schema, no annotations, and no parameters, it should ideally clarify the return value or behavior when the subscription is absent. These gaps are minor given the tool's low complexity.

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 takes zero parameters, so there is no parameter information needed. Per the rubric, zero parameters yields a baseline of 4 when the schema coverage is complete, which it is (100%).

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 ('Check') and resource ('status of the Pro subscription'), and scopes it to the current MCP session. This distinguishes it from the sibling 'subscribe' tool, which would initiate a subscription rather than read its status.

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?

Implies usage context (checking status of the current session's Pro subscription), but does not explicitly state when to use it versus alternatives like 'subscribe' or what conditions trigger the call. No exclusions or prerequisites are mentioned.

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