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

The description contradicts the annotations. Annotations declare readOnlyHint=true, yet the description says 'Calling it records that an upgrade link was requested,' which implies a state-changing side effect. Even though the description usefully discloses that the link contains no credentials, the direct contradiction with readOnlyHint makes the behavioral model unreliable.

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 three sentences long and every sentence earns its place: purpose and trigger, link behavior and security property, and user-facing action plus side effect. It is front-loaded with the core purpose and contains no filler.

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 with an output schema, this description covers the essential context: what the link does, when to use it, what to do with it, and that it has no credentials. The only weakness is the readOnlyHint contradiction, which makes the side-effect information conflict with the annotations.

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 has zero parameters and schema coverage is 100%, so there is no parameter semantics for the description to add. With no parameters, a baseline of 4 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 opens with a specific verb and resource: 'Get a link to upgrade the account's plan on the Lumethic website.' It also gives concrete trigger examples (QUOTA_EXCEEDED or NOT_ENTITLED errors) and tells the agent to show the link to the user. This is clearly differentiated from sibling tools like get_account_usage or get_listing.

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 explicitly identifies when to use the tool: after quota or entitlement errors, and states that the link should be shown to the user. It does not mention when not to use it or name alternative tools, but the context is clear enough for an agent to make the right call.

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