check_upgrade_eligibility

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

No annotations are provided, so the description must carry the full burden. It discloses authentication requirements, which is useful, and hints at the output (eligible date and fees). However, it does not explicitly state whether this is a read-only operation or if there are any side effects, relying on the verb 'check' to imply safety.

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, focused sentence that front-loads the action and purpose, then adds relevant details (eligible date, fees, credentials). There is no fluff or redundant information.

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?

For a tool with three parameters and no output schema, the description is mostly complete: it explains the purpose, output highlights, and authentication. However, it does not describe the behavior when the optional line_number is omitted, nor does it fully detail the return structure beyond eligible date and fees, leaving some room for ambiguity.

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 schema description covers 100% of parameters, so the baseline is 3. The description adds little beyond the schema, only implicitly connecting 'line' to the optional line_number parameter. It does not provide additional semantic detail about the parameters, so it remains at 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 clearly specifies the tool's function: checking upgrade eligibility for a line on an AT&T account, including eligible date and upgrade fees. This is a specific verb+resource+scope that distinguishes it from sibling tools like get_account_overview or pay_bill.

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 provides clear context for when to use the tool (to check upgrade eligibility) and notes a prerequisite (AT&T login credentials). However, it does not explicitly mention alternatives or when not to use it, which would have made it a 5.

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