get_balance

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

No annotations are provided, so the description carries the full disclosure burden. It states it returns balance and spending totals, which implies a read-only operation. However, it does not describe the return format, whether spending totals are date-scoped, or any rate-limit/auth requirements. It's adequate but thin.

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?

A single sentence with zero waste. It efficiently communicates the resource (Farebox), the action (Get balance and spending totals), and the unit (USD). No filler or redundant phrasing.

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 tool with a clear purpose and no output schema, the description is mostly sufficient. It explains what is returned (balance and spending totals in USD). It could add a note about whether spending totals reset or cover a specific period, but given the simplicity of the tool, this is a minor 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?

There are zero parameters, so the baseline is 4 per the rubric. The description adds value by clarifying that the tool requires no input and returns balance plus spending totals in USD, going beyond the empty schema. Score 5 is justified because with no params, nothing is needed.

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's purpose with a specific verb ('Get') and specific resource ('Farebox account balance and spending totals in USD'). It distinguishes itself from siblings like get_usage by focusing on Farebox account balance specifically rather than general usage metrics.

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 when to use this tool (when you need account balance/spending totals) but provides no explicit guidance on when NOT to use it or which sibling tools to use instead. get_usage is a natural alternative, but no differentiation is provided.

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