Account balance

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds the return envelope structure ({ok, message, next_tool, next_args, ...}) and the conversion behavior, which goes beyond the annotations. It does not over-explain or contradict them.

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?

Two tight sentences: the first lists what the tool reports, the second shows the return format. No filler, and the most important information is front-loaded.

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 read-only, zero-required-parameter balance lookup with a documented optional parameter and an explicit return structure, nothing an agent needs to invoke it correctly is missing. The output schema and annotations cover the rest.

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%: usd_per_hour is fully documented with type, description, and default. The description adds a light reference to 'a given rate' but does not need to elaborate further since the schema carries the semantics.

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 enumerates the resource (prepaid credit, cash balance, lifetime spend) and the derived output (GPU-hours at a rate). It is immediately distinguishable from sibling tools like list_instances or get_instance, which concern instances rather than account financials.

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 conveys the natural use case - checking balance and converting it to GPU-hours - but does not explicitly state when to use it versus alternatives, nor does it mention any exclusions. Usage is implied rather than directed.

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