surface_patch

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

With no annotations, the description carries the full behavioral burden and does so well: it documents error behavior including INVALID_PARAMS with no changes and FUSION_API_ERROR with rollback, notes that surface body refs change after trim/extend/stitch, and describes the return structure.

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 and then organized into refs, next steps, errors, returns, and an example. Every paragraph contributes actionable information for a complex modeling operation, with no wasted prose.

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 five-parameter modeling tool with no output schema and no annotations, the description covers boundary forms, continuity semantics, reference freshness, error behavior, return shape, and follow-up operations. An agent has enough information to call the tool correctly and interpret common outcomes.

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 coverage is 100%, so the schema already documents parameters, but the description adds meaningful semantics for the boundary forms and clarifies that continuity, weight, and flip apply to body edges and are ignored for sketch curves. The operation parameter is left mostly to the schema enum, so this is strong but not fully exhaustive.

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 verb and resource: 'Patch surface: fill a closed boundary with a new surface body (Patch feature).' It clearly distinguishes the operation from related surface and body tools by naming next steps such as surface_stitch and body_thicken.

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?

It gives clear usage context: boundary can be a sketch profile, sketch curves, or B-Rep edges, and continuity/weight/flip apply only to body edges. It also names follow-up tools for closing and thickening surfaces, though it does not explicitly exclude alternatives like body_boundary_fill or surface_ruled.

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