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

With no annotations provided, the description carries the full burden. The word 'Check' implies a read-only operation, and the description adds useful detail (currency and account status), but it does not explicitly state that no credit is consumed or that the call has no side effects.

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 words. Every part adds information: the action, the resource, the currency, and the additional status check.

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 zero-parameter getter with no output schema, the description covers the essential returned information (balance and account status) and leaves no major ambiguity about what the tool does. No additional caveats or preconditions are needed for a simple read-only balance check.

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, which is the baseline 4 case. The description correctly avoids inventing parameters and simply states what the tool looks up.

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 ('Check') and names the exact resource ('remaining SMS credit balance in MAD') plus the secondary result ('account status'). This clearly differentiates it from siblings like send_sms, get_analytics, or create_topup.

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?

Although it does not explicitly mention alternatives or exclusion conditions, the intended context is obvious: call this tool whenever the remaining SMS credit or account status is needed. There is no competing sibling that does the same thing, so no stronger routing is necessary.

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