subscribe

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

With no annotations, the description carries the full burden. It states the action (subscribe) and the subject (email) but does not disclose side effects such as confirmation emails, idempotency, data handling, or potential errors. However, the core behavior is clear, and the description adds context about the newsletter's content. It's adequate but lacks deeper behavioral detail.

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, well-structured sentence that includes the action, target, source, and newsletter content. Every word adds value; there is no fluff or repetition. It is concise yet informative.

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 one-parameter subscribe tool, the description covers the essential purpose and gives context about the newsletter. It lacks details about post-subscription behavior (e.g., welcome email, unsubscribe instructions), but these are not critical for invoking the tool. The given schema is sufficient, and the description is adequate for a typical use case.

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 covers 100% of the parameter documentation, with the 'email' property described as 'Email address to subscribe.' The description adds no additional semantic value beyond naming the recipient type ('user email'), which is redundant. Baseline 3 is appropriate for full schema coverage.

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 ('Subscribe') and clearly identifies the resource ('a user email to The Weekly Index newsletter from SkillsIndex'). It also differentiates from sibling tools by focusing on newsletter subscription rather than tool search/compare/submit operations.

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 clear context about the newsletter's content (weekly digest of AI agent tools, security alerts, and honest picks), making it obvious when subscription is appropriate. It doesn't explicitly state when not to use it, but the purpose is unambiguous. No exclusions are mentioned.

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