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

With no annotations, the description carries full responsibility for disclosing behavior. The only behavioral hint is '1 Credits' per call, which might indicate a cost, but it is not explained and does not cover side effects, permissions, or return behavior. The description provides almost no meaningful 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 extremely short (one sentence), which is concise, but it under-specifies the tool. The sentence 'Search Billing per call: 1 Credits.' does not earn its place because it provides minimal value and leaves critical information unresolved. It reads more like an incomplete note than a helpful description.

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?

Given the simple structure with 2 optional parameters and no output schema, a well‑written description could easily be complete. However, this one fails to explain what the tool does, what parameters mean, or what results to expect. The lack of annotations and output schema increases the burden, which the description does not meet.

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?

Schema description coverage is 0% — the description does not mention 'code' or 'number' at all. Since the parameters have no commentary and are optional, the agent is left without any semantic understanding of what these parameters represent or how to use them. The description fails to compensate for the schema's lack of detail.

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 is vague: 'Search Billing per call: 1 Credits.' It states the verb 'Search' and mentions 'Billing' but does not clarify what entity or data is being searched, nor what the search returns. Without sibling tools, it fails to distinguish itself. It is not a pure tautology but is too ambiguous to convey a clear purpose.

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 about when to use this tool, what scenarios it is appropriate for, or any alternatives. The description does not mention any conditions or exclusions. Since no sibling tools exist, it still lacks any usage context, making the agent unable to decide when to invoke it.

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