Plan and billing

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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds genuinely useful context: it discloses the exact return content (personal upgrade/change-card/cancel links) and clarifies the subscription-vs-ad-spend boundary. It doesn't mention auth or rate-limit behavior, keeping it short of a 5.

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?

Two dense sentences, front-loaded with the resource and its contents, then the scope boundary. Every clause conveys actionable detail (tiers, links, exclusions) with no waste.

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, the description carries the job of explaining return values, and it does: it lists what is shown and the personal links returned. Combined with the read-only annotations, an agent has everything needed to call and interpret it.

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 the baseline is 4, and there are no parameter semantics for the description to compensate for. Nothing is missing on this dimension.

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 names a specific verb and resource ('Shows the user's Camberstack plan') and details exactly what is surfaced: accounts used vs plan limit, the plan tiers (Free 1, Plus 1, Pro 5, Agency 25), and the Free-service coverage. This distinguishes it clearly from every sibling tool, none of which handle billing.

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?

It provides an explicit exclusion ('This is the Camberstack subscription only, not a Google Ads account's own billing, invoices or ad spend'), which routes the agent away from misusing it. There is no named alternative to use instead, so it lacks the sibling-comparison required for a 5, but the negative scoping is clear.

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