add_sphere

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

Since no annotations are provided, the description carries the full burden of behavioral disclosure. It explicitly warns that the tool updates the JCAD document and instructs the user to read the current state first. It also mentions the return value, which is the document itself. This is stronger than typical but lacks details on error behavior or permanence.

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 clear opening, parameter list, and warning section. The angle explanations repeat across three parameters but add necessary detail. Overall, it is appropriately sized with no filler, though slightly repetitive.

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?

For a 10-parameter tool with no output schema and no annotations, the description covers the essential aspects: purpose, parameter semantics, return value, and side-effect warning. It lacks details on units, coordinate system, and a few parameter nuances, but these are minor gaps given the overall coverage.

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?

With 0% schema description coverage, the description steps in with explanations for 9 of 10 parameters. It provides meaningful semantics for angles (degrees and effect on sphere shape) and color (hex or RGB list). However, position and rotation_axis remain vague ('The shape 3D position' and 'The 3D axis used for the rotation'), and jcad_path is missing from the param list even though it is referenced in the warning.

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 states a specific action and resource: 'Add a sphere to the document.' This clearly conveys the tool's purpose. However, it does not differentiate this tool from sibling tools such as add_box or add_cylinder, so it misses the top score.

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: 'To understand the current state of the document, you MUST first use the get_current_cad_design tool.' This gives useful context for when to use the tool. It does not mention explicit alternatives or when-not-to-use scenarios, so it stops short of a 5.

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