get_billing

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

With no annotations, the description carries the full behavioral burden. It does disclose the scope of returned data, including that usage figures are period-scoped ('this period'), which is genuinely useful context. However, it says nothing about read-only safety, permission requirements, or how the billing period is defined, leaving real gaps for a no-annotation tool.

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?

A single front-loaded fragment with no padding, and the most important concept (plan/subscription) comes first. It is arguably too terse as a fragment rather than a sentence, keeping it out of 5 territory.

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?

No output schema exists, so the description must convey return contents, and it does list the main fields. But it omits any usage guidance relative to get_overview/whoami and any behavioral notes, leaving the definition only minimally complete for a billing endpoint.

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 by rule. The description correctly adds no parameter guidance because none is needed; the empty schema is self-explanatory.

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 name supplies the verb (get_) and the description specifies the resource contents: plan, subscription status, and usage counters for email sends and AI drafts. That is enough for an agent to know this returns account/billing state. It stops short of naming a sibling, so it does not reach 5.

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 no indication of when to call this versus adjacent tools such as get_overview or whoami, which likely surface overlapping account context. No prerequisites, no conditions, no exclusions are stated.

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