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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds two things annotations cannot express: the required billing:read permission and the privacy boundary (no personal or payment details returned). It does not say what happens on a missing permission, which costs it the top score.

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?

Three short sentences: what it reads, when to call it, and the permission/privacy constraints. Front-loaded with the resource and field list, zero 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?

There is no output schema, so the description carries the burden of describing the return, and it does so at a field-category level (plan, expiry, capacity, permissions) plus an explicit exclusion. Exact response shape is unstated, a minor gap for a read tool with no inputs.

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. The description wastes no effort inventing parameter guidance and instead spends its words on scope and permissions.

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?

States a specific verb+resource (read the connected account) and enumerates exactly which fields are returned: plan, expiry, board capacity, permissions. This is clearly distinguishable from the sibling tools, which all concern scoreboards and checkouts rather than account/billing state.

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?

"Call before offering a paid upgrade" gives an explicit triggering condition, which is more than most definitions offer. It stops short of naming alternatives or a when-not case, but for a zero-parameter read there is little else to route against.

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