list_modules

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

There are no annotations, so the description carries the full burden. It discloses that the tool lists all available modules and includes class counts, implying a read-only operation. It does not mention side effects or permissions, but for a straightforward listing tool, this is sufficient. The 'all available' and 'with class counts' details add behavioral specificity beyond the tool name.

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. The first sentence front-loads the core purpose, and the second provides usage guidance. There is no redundancy or unnecessary information, making it highly concise and well-structured.

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 (no params, output schema exists). The description covers the purpose and usage context, including a pointer to the resource used for retrieving class details. This is complete for the tool's complexity and does not need to explain return values thanks to the output schema.

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, and the schema confirms this. The baseline for a zero-param tool is 4, and since there are no parameter descriptions needed, the description appropriately omits param details. There is nothing to add beyond the schema.

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 'List all available Unreal modules with class counts' which identifies a specific action (list) and resource (Unreal modules) with a distinguishing detail (class counts). This separates it from sibling tools like get_class_overview (which retrieves classes for a specific module) and list_unreal_instances (which lists engine instances).

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 explicitly tells the agent when to use this tool ('Use this to discover what modules are available') and provides a clear next step ('then use unreal-python://index/module/{name} resource to get classes for that module'). This gives both a use case and a pointer to an alternative resource, satisfying the 'when-to-use' and 'alternatives' criteria.

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