Credit Correction

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains the critical semantics of the amount parameter ('amount is added to the current balance; use a negative value to subtract') and the permission requirement. It does not mention reversibility, idempotency, or error cases, but for a straightforward balance adjustment, the key behavior is disclosed.

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 extremely concise—two short sentences totaling 22 words. The core purpose is front-loaded in the first sentence, and the second sentence adds crucial operational detail. Every word earns its place; there is zero fluff or redundancy.

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 (3 parameters, no nested objects, no output schema), so the description need not be elaborate. It covers the main behavior and the permission prerequisite. However, it omits any indication of success/failure response, whether the operation is reversible, or any validation constraints (e.g., max/min amount). Given the availability of sibling tool get_credit, a note about verifying the change after the call would improve completeness. It is adequate but not fully comprehensive.

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 has 0% description coverage, so the description must compensate. It explains 'amount' behavior clearly, and 'sub-user' implies that 'username' refers to a sub-user. However, the 'reason' parameter is entirely unexplained, and the description does not elaborate on the expected format or constraints for username or amount beyond the sign semantics. The compensation is partial at best.

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 function: 'Adjust a sub-user's credit balance.' The verb 'adjust' and the specific resource 'sub-user's credit balance' make the purpose distinct from sibling tools like get_credit (which reads credit) and info_user. It immediately communicates what the tool does and its scope.

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 a key usage condition: 'Requires SUBREG_READONLY=false.' This tells the agent when the tool can be used (when permissions allow) but does not explicitly contrast it with alternatives or state when not to use it. The context is clear and actionable, but it lacks explicit exclusion guidance, preventing a 5.

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