Check the credit balance

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

With no annotations provided, the description carries the burden of disclosing behavior. 'How many credits the account has' implies a read-only query with no side effects. It also adds useful context about the credit system (charges per 1,000 words and 10-credit minimum), which helps the agent judge when to check. It does not mention return format, but for a simple balance check 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 sentences and front-loaded. The first sentence states exactly what the tool does. The second sentence provides relevant cost information and a usage tip, earning its place. No wasted words.

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?

This is a simple tool with no parameters and no output schema. The description fully covers its purpose, provides usage guidance, and gives background on credit consumption. The sibling tools are all credit-consuming operations, so the 'before a large document' tip is sufficient contextual guidance. Nothing important is missing.

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 has zero parameters, so schema coverage is 100% by default. The baseline for 0 params is 4. The description adds value by explaining the credit cost model, which gives context for interpreting the balance, even though it is not parameter-specific.

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: 'How many credits the account has.' This is a specific read operation with a clear resource (credit balance). It is distinct from all sibling tools, which perform document operations or job checks, so there is no ambiguity.

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 provides usage context: 'Worth checking before a large document.' This signals when to use the tool relative to the credit-consuming sibling tools. It does not explicitly name alternatives or exclusions, but the context is clear and actionable.

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