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

With no annotations provided, the description carries the full behavioral disclosure burden. It does state 'Read-only' and clarifies the credit unit and the relationship to Studio credits, which is useful. It does not mention error behavior, return format, or potential ambiguity around 'unless the wallet was claimed,' but for a simple balance read this is acceptable.

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 short sentences with no filler. It front-loads the core resource, then adds the unit, the credit distinction, and the read-only trait—each 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?

For a simple one-parameter read-only balance tool, the description covers the essential context: what is being queried, the unit of measurement, and how it relates to another credit system. It does not specify the exact return format, but the meaning of 'balance' is clear enough without an output schema.

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 already fully documents the sole parameter, including how to obtain the key and that read scopes suffice. The description adds some context about the wallet relationship but does not significantly extend the parameter semantics beyond the schema's rich description.

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 identifies the resource as the cloud credit balance of the wallet behind a compute API key, with a useful unit clarification (1 credit = $1). It distinguishes this from Studio platform credits, though it lacks an explicit verb like 'get' or 'retrieve'.

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 gives helpful context by separating cloud credits from Studio platform credits, which helps an agent know when this tool applies. However, it does not explicitly state when to use this tool versus siblings like cloud_credit_activity or other cloud usage tools, nor does it mention any alternatives.

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