add_assembly_part

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 describes the behavior: parsing JSON, appending the part, and returning the updated state. It mentions that the assembly is 'existing' and that the result is 'updated assembly state', implying immutability. While it could add more about error handling or permissions, it adequately discloses the core 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 well-structured with a docstring format: purpose, process, then parameter list. It is slightly long but each sentence adds value. The front-loaded purpose is clear. It could be more concise by grouping defaults, but it is not overly verbose.

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?

With 8 parameters, 3 required, and no output schema, the description covers all parameters and the return value (updated assembly state). It explains the process and default values. It lacks details on constraints (e.g., part_id uniqueness) or error scenarios, but for a moderately complex tool, it is sufficiently complete.

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%, so the description must add meaning. It fully describes each parameter: assembly_json (state from previous tool), part_id (unique identifier), file_path (mesh file path), position offsets, material (filament material), role (structural role). This provides essential context beyond the schema's property names and types.

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 'Add a part to an existing assembly' with a specific verb and resource. It explains the process of parsing JSON, appending, and returning updated state. It distinguishes from sibling tools like create_assembly (creates new) and add_assembly_interface (adds interface).

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 implies that the assembly must already exist by specifying that assembly_json comes from create_assembly or previous tool calls. However, it does not explicitly state when to use this tool vs alternatives like add_assembly_interface or when not to use it. Guidance is implied but not explicit.

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