mmar_create_class_instance

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

No annotations are provided, so the description carries the full burden. It discloses a critical non-obvious behavior: 'The API does NOT auto-create attribute instances. You MUST include them in the payload.' This prevents a common failure. It does not mention response format or error cases, but the warning is highly valuable.

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 front-loaded with the purpose, then a bolded IMPORTANT warning, and finally an example. The example is lengthy but directly useful for constructing the payload. No wasted sentences; the structure is logical and readable.

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 tool's complexity (nested attribute instances) and lack of an output schema, the description thoroughly explains the input requirements. It does not cover return values or error handling, but for a creation tool with no output schema, the input focus is appropriate. The warning about attribute instances makes it complete enough to use correctly.

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 schema already provides descriptions for both parameters, so coverage is 100%. The description adds further semantic value by explaining the required structure of the JSON string and giving a concrete payload example, especially the attribute_instance array with uuid, name, value, and uuid_attribute. This goes beyond the schema's brief property descriptions.

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 starts with 'Create a new class instance (element/node) within a scene instance,' providing a specific verb and resource with clear scope. This distinguishes it from sibling tools like mmar_create_scene_instance or mmar_create_attribute_for_class.

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 does not explicitly state when to use this tool vs. alternatives, but the purpose and the important note about attribute instances imply when it is needed. It would benefit from saying 'Use this to add an element to an existing scene instance' and possibly contrasting with update or delete operations.

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