QR for Agent

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

With no annotations provided, the description carries the full burden and succeeds in disclosing key behavioral traits: it returns a portal URL (not performing actions directly), requires the user to open it in their browser (UX flow), and has a strict prerequisite check (Pro subscription). It could improve by mentioning what happens if called without Pro (error vs. silent failure) or whether the URL is single-use.

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?

Three sentences, each earning its place: sentence one establishes purpose, sentence two explains the return value and user interaction pattern, sentence three states the prerequisite. Information is front-loaded with the action verb, and there is no redundancy or wasted prose.

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 tool lacking an output schema, the description fully compensates by explaining exactly what gets returned ('portal URL') and how it should be used ('tell the user to open it in their browser'). The prerequisite constraint is also documented. Given the tool's simplicity, this is sufficiently complete.

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 input schema contains zero parameters. According to the rubric, 0 parameters establishes a baseline score of 4. The description correctly does not invent parameter semantics where none exist.

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 uses a specific verb ('Open') with a specific resource ('Stripe billing portal') and lists concrete actions ('manage your subscription, update payment method, or cancel'). It clearly distinguishes from all QR-code-related siblings and contrasts with 'upgrade_to_pro' by focusing on management of existing subscriptions rather than upgrading.

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 provides explicit constraints ('Only works if you have an active Pro subscription') which functions as a when-to-use prerequisite. However, it stops short of explicitly naming 'upgrade_to_pro' as the alternative for users without a Pro subscription, which would have made the guideline vs. alternatives distinction perfect.

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