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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds context beyond them: the auth scope needed (billing:write) and a clarification that the returned link does not mint a Stripe portal session. It still doesn't say whether the link expires or 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?

It is short and the exclusion is front-loaded, but the opening sentence is a verbless fragment that reads as a continuation rather than a definition, forcing the agent to reconstruct the purpose from the name.

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?

With no output schema and no parameters, the description carries the full burden of explaining the return value, yet it never says what a 'billing link' is (URL string? object with expiry? one-time?). The auth and exclusion notes are helpful but the result shape is left unspecified.

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 nothing for the description to disambiguate; baseline 4 applies. The auth-scope note is the only input-adjacent detail and it is present.

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 describes the destination ('where the merchant manages their subscription') but never states the actual action, that the tool returns a billing link/URL. The name and title carry most of the meaning; the text distinguishes it from get_connection_link and get_subscription only implicitly by topic.

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?

There is a useful negative constraint ('It does NOT open Stripe's portal: that session is minted on the API') and a prerequisite ('Requires billing:write'), but no positive statement of when to call this versus get_subscription or get_connection_link.

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