get_bill_history

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

No annotations are provided, so the description alone must convey behavioral traits. 'View' signals a read-only operation, but the description does not disclose authentication requirements, that external T-Mobile credentials are used, login failure behavior, or any response/pagination characteristics.

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 a single front-loaded sentence with no filler, repetition, or irrelevant detail. Every word earns its place.

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 annotations, the description leaves the agent without information about the return value shape, pagination/volume, or the authentication flow implied by the username/password parameters. For a three-parameter tool that accesses an external T-Mobile account, this is a meaningful gap.

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 input schema describes all three parameters (months, username, password) at 100% coverage, so the description does not need to add parameter details. The tool description itself adds no parameter meaning beyond the schema, matching the baseline.

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 uses a specific verb ('View') and a clear resource ('past T-Mobile bills and payment history'), which tells the agent what the tool retrieves. It is distinguishable from siblings like pay_bill, but it does not explicitly call out sibling tools to reinforce the boundary.

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 wording implies this is for read-only historical billing/payment access. It contrasts with pay_bill or get_usage_details, but there is no explicit statement of when to choose this tool or when an alternative is preferred.

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