fusion_add_fillet

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 does not disclose behavioral traits such as whether the operation modifies the body in place, is reversible, requires specific permissions, or has any side effects. It only describes inputs and gives an example. This is insufficient for a mutating tool.

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 concise and efficient. It leads with a clear one-sentence purpose, then dedicates lines to the edge_selector parameter, which is the only non-trivial part. Every sentence contributes to understanding, with no fluff. The structure is well front-loaded.

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 moderate complexity (3 params, nested object) and no output schema, the description covers the essential usage. It explains the main selector mechanism and references helper tools. However, it does not mention expected side effects (e.g., fillet applied to solid body) or error conditions, and it does not clarify the units for radius_mm. These gaps are minor because the purpose is clear, but there is room for improvement (e.g., stating the operation modifies the body).

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 has zero description coverage, so the description must add meaning. It excels at explaining edge_selector, which is the only complex parameter, with detailed JSON examples and a caveat about 'midpoint lies within max_distance_mm'. It does not explain body_id or radius_mm, but these are straightforward (ID string and numeric radius). The description adds significant value beyond the schema for the key parameter.

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 'Round edges with a fillet.' which is a specific verb+resource statement. It clearly distinguishes this tool from siblings like fusion_add_chamfer (which would be for chamfering). The purpose is unambiguous.

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 concrete usage guidance for the complex edge_selector parameter, with examples for 'all_edges' and 'near_points'. It references helper tools (mesh_tools.find_circular_holes/faces, fusion_get_body_info) for obtaining points, implying typical use cases. However, it does not explicitly state when NOT to use this tool or mention alternatives like fusion_add_chamfer, so it lacks explicit exclusions but is still clear.

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