List Regions

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It only states the operation is a list of enabled regions and requires a prior call. It does not describe what happens if the inventory is not loaded (e.g., error behavior), nor does it mention any other traits like idempotency, rate limits, or whether the output is a simple list of region names. For a tool with zero annotation coverage, this is insufficient.

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 with no wasted words. The first sentence front-loads the core purpose, and the second immediately provides the critical prerequisite. Every sentence earns its place.

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 has no output schema, so the description should explain return values. It states 'List enabled AWS regions' but does not describe the format of the output (e.g., list of region names, objects, or something else). It also does not mention error conditions or edge cases. Given the tool's simplicity, the missing output description is a gap, but the prerequisite and purpose are covered, making it minimally adequate.

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?

There are zero parameters, so the input schema is trivially fully covered. The description does not need to add parameter semantics because none exist. According to the rules, 0 params gives a baseline of 4, which is appropriate here.

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 verb and resource: 'List enabled AWS regions from the loaded inventory.' This explicitly distinguishes it from siblings like 'scan' (data ingestion), 'load' (data loading), and 'export' (data output), as it is a read-only retrieval operation on already-loaded data.

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 clear prerequisite: 'Requires "scan" or "load" to be called first.' This tells the agent when to use the tool (after data loading) and implicitly not to use it before. However, it does not mention alternatives or when-not scenarios beyond the prerequisite, which keeps it from being a 5.

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