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

No annotations are provided, so the description carries the burden, but 'Read' plus 'current balance' does convey a non-mutating, point-in-time query with no side effects. It omits auth requirements, rate limits, and whether the balance is account- or project-scoped, which for a billing-related read would be useful context.

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 front-loaded sentence with no filler; every word earns its place. Appropriate size for a zero-argument read.

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?

With no annotations and no output schema, the description is the only source of information, and it does not describe the return shape (units, currency, formatting) or how it relates to codebase_get_usage. For a trivial zero-param read this is close to adequate, but the sibling ambiguity and missing return context leave gaps.

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 nothing for the description to disambiguate. No additional parameter semantics are needed or missing.

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 states a specific verb ('Read') and resource ('the current Codebase credit balance'), so the agent knows exactly what it returns. It does not differentiate itself from the sibling codebase_get_usage, which is a plausible alternative for similar billing/quota information.

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?

There is no guidance on when to use this tool versus codebase_get_usage or any other sibling, and no stated prerequisites. The agent must infer the use case purely from the tool name.

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