Get Account Balance

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

The description adds the important behavioral note that the tool requires an API key, which is beyond what annotations provide (readOnlyHint, idempotentHint). It correctly implies a safe, non-destructive operation. No contradiction with annotations.

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 long with no unnecessary words. It front-loads the core purpose and follows with a critical requirement. Every sentence 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?

Given the simplicity of the tool (one optional parameter, no output schema) and rich annotations, the description is mostly complete. However, it does not hint at the return format, but the tool name and context imply a numeric balance value. A minor gap but not critical.

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 has 100% coverage for its single optional parameter 'currency', so the description does not need to add extra meaning. The baseline score of 3 is appropriate as the description ignores the parameter entirely.

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 verb 'Check' and the resource 'account balance in USD', which immediately distinguishes this tool from siblings like get_price or get_profile. The resource is specific and easy to understand.

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 mentions a prerequisite (VIRTUALSMS_API_KEY) but does not provide guidance on when to use this tool versus alternatives. The context of sibling tools suggests it is for balance inquiry, but no explicit when-to-use or when-not-to-use advice is given.

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