Get the credit balance

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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds two genuinely new facts: the unit conversion (1 credit = 1 grid point) and that the call is free, which is cost/rate context not present in the annotations. However, it says nothing about auth requirements, return format, or whether balance can be negative or stale.

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?

Three short fragments, front-loaded with the core fact (what the balance is) followed by unit clarification and cost. No filler. Slightly terse to the point of reading as a label rather than a sentence, which costs a point.

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?

The tool is simple and the annotations cover read-only safety, so little is needed. But with no output schema, the description does not say what the balance looks like on return (a number, a formatted string, a per-workspace breakdown), leaving a small but real gap for an agent consuming the result.

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, so the baseline is 4. There is no parameter surface for the description to compensate for, and the '(1 credit = 1 grid point)' note usefully clarifies the semantics of the returned value's unit.

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?

States a specific resource and what it returns: 'Credits left on the account.' An agent can tell this is a read of account balance and distinguishes it from the grid/schedule siblings, which do entirely different things. It is phrased as an output description rather than a verb+resource, but the intent is unambiguous.

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?

No when-to-use or when-not-to-use guidance is given, and no alternatives are named. 'Free' hints that calling it has no cost, which is mildly useful, but nothing tells the agent when to reach for this versus estimate_grid or run_grid.

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