purchase_article

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

With no annotations provided, the description carries the full burden. It discloses that the tool returns a Stripe Checkout URL rather than completing the purchase immediately, which is a key behavioral trait. However, it does not describe other important aspects such as authentication requirements, side effects, or error conditions.

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 a single, front-loaded sentence that conveys the essential information. There is no superfluous text, making it highly concise and effective.

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 simple tool with one parameter and no output schema, the description is fairly complete. It explains the return value (Stripe Checkout URL) and the overall purpose. However, it lacks details about potential errors or prerequisites like login status, which would enhance completeness.

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 schema description coverage is 100% for the single parameter 'article_id', with a clear description. The tool description adds that the article must be paid, which is not captured in the schema, but this is marginal. The parameter semantics are adequately handled by the schema, so a baseline score of 3 is appropriate.

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's function: 'Purchase a paid article (returns Stripe Checkout URL)'. It uses a specific verb and resource, and distinguishes itself from sibling tools which are for other actions like bookmarking, searching, or commenting.

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 implies the tool should be used when a user wants to purchase a paid article, but it does not provide explicit when-to-use or when-not-to-use guidance, nor does it mention alternatives. The context is clear only through the tool's name and description.

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