Read a credit's current balance + expiry

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

The description discloses important behavioral details beyond a simple read: it explains that the tool is free, that anyone with the creditId can access it (security implication), and that 404 errors intentionally blur malformed UUIDs and non-existent credits to prevent enumeration. This is valuable transparency.

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 long, front-loading the key information (free, return fields) and then adding security notes. Every sentence serves a purpose; no redundancy or filler. It is maximally efficient for its informational load.

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 read tool with one parameter and no output schema, the description is complete: it lists the return fields, explains the access model, and addresses security. Given the low complexity and good schema coverage, no additional context is needed.

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 describes the creditId parameter with format and origin. The description adds meaning by framing the parameter as a secret that gives anyone holding it read access, echoing the decrement permission model. This enhances the parameter's semantic context.

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 title and description clearly state the tool reads a credit's balance and expiry. It lists the returned fields, making the purpose explicit. However, it does not explicitly differentiate from siblings like buy_credits or preflight, leaving some ambiguity for an AI agent.

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 notes that no payment is required and that anyone with the UUID can read state, but it does not provide explicit guidance on when to use this tool versus alternatives like buy_credits or forensics. There is no mention of prerequisites or when not to use it.

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