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

With no annotations, the description carries the full burden of behavioral disclosure. It only states 'without charging,' which hints at a non-billing operation but does not clarify if it's read-only, what side effects exist, or what the response structure is. This is insufficient for an agent to predict the tool's behavior.

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 a single concise sentence that front-loads the action. It contains no redundant words and is easy to scan. It earns a high score for economy.

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 lack of an output schema and annotations, the description should explain what the returned boundaries and purchase routes look like or what they represent. It does not, leaving an agent uncertain about how to use the result. The tool is simple (no params) but the description still feels incomplete.

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 the schema is empty and the baseline for this dimension is 4. The description correctly avoids inventing parameters and adds no param information, which is appropriate. There is no gap to compensate for.

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 uses a specific verb 'Return' and names a resource ('free and paid boundaries and purchase routes'), so it is not a tautology. However, 'boundaries' and 'purchase routes' are ambiguous and the description does not differentiate it from siblings like fluxproof_preflight or fluxproof_check_now. The purpose is somewhat clear but lacks precision.

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 gives no indication of when to use this tool versus any of its siblings. There is no mention of context, preconditions, or alternative tools, leaving the agent to guess. Even a simple tool should state whether it's for pricing info, plan limits, or purchase flows.

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