add_spline_component

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

Annotations already declare destructive=true, idempotent=false, readOnly=false, so the safety profile is covered. The description adds real behavioral value by disclosing the construction sequence and, critically, that supplying points clears the default points and adds each in local space — a mutation detail the annotations do not convey. It stops short of describing failure modes or eligibility constraints on the target actor.

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?

Front-loaded with the core action and return shape, then the behavioral detail. The middle sentence enumerating NewObject/RegisterComponent/AddInstanceComponent/CreationMethod=Instance is largely internal engine plumbing, but it is compact and does explain the resulting component's creation semantics.

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 no output schema, the inline Returns block is genuinely useful, and the points-replacement behavior is disclosed. What is missing is the precondition set — that the named actor must exist in an editor world and what happens if it does not — which matters for a destructive, non-idempotent tool.

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 100% and both parameters are documented in the schema, including that points are local-space [[x, y, z]] arrays. The description's 'in local space' phrasing duplicates the schema rather than extending it, so the baseline 3 applies.

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?

States a precise verb (adds) and resource (USplineComponent) plus the target (a named editor-world actor), which cleanly separates it from siblings like add_spline_mesh_component and set_spline_points. An agent can identify the operation without opening the schema.

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?

No explicit when-to-use or when-not-to-use guidance and no mention of alternatives such as add_spline_mesh_component. The only contextual hint is the phrase 'editor-world actor,' which weakly implies a prerequisite (actor must already exist, editor world required) but never states it.

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