get_usage_details

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the need for login credentials, but does not explicitly state that this is a read-only operation, what happens with invalid credentials, or any side effects. For a get tool, more transparency about its non-destructive nature would be expected.

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 two sentences, directly states the purpose, and includes the key prerequisite. It is front-loaded with the action and scope, with no wasted words.

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?

Given the tool's simplicity and lack of output schema, the description adequately covers the returned content (data, call, text usage) and the time scope (current billing period). It also mentions required credentials. However, it could be more complete by explicitly noting the read-only nature or possible absence of output for empty usage.

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?

Schema coverage is 100% with both username and password described. The description does not add additional meaning beyond the schema, so a baseline of 3 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 clearly states the tool gets a detailed breakdown of data, call, and text usage for the current billing period. This specific verb+resource+scope distinguishes it from sibling tools like get_account_overview or get_bill_history.

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 implies usage when you need current usage details, but it does not explicitly say when to use this tool versus alternatives. The mention of AT&T login credentials is a prerequisite, not usage guidance against other tools.

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