spawn_niagara_component

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

Annotations already declare the safety profile (readOnly=false, destructive=false, idempotent=false), so the bar is lower. The description still adds real value by disclosing that bAutoDestroy is disabled and the component persists, plus the exact return fields. It does not spell out that repeated calls create new components (non-idempotent) or note that owner_actor_name/label becomes the handle for later calls, leaving a small gap.

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?

Three front-loaded sentences: purpose, persistence mechanism, then how to re-target the owner, followed by the return shape. The SpawnSystemAtLocation reference is a minor implementation aside but each sentence carries information an agent needs.

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 spawn/mutation tool with no output schema, it supplies the return shape inline and explains the persistence behavior that governs follow-up calls. It could be slightly richer on failure modes (invalid system_path) but is otherwise complete enough to invoke correctly.

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 the schema itself carries the important rotation warning about the [pitch, yaw, roll] array form, so the schema does the heavy lifting. The description introduces the naming concepts (owner_actor_name/owner_actor_label) that map loosely to the actor_label param, but adds no syntax or format detail beyond the schema, so 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 specific verb (spawns) and resource (a Niagara System as a persistent UNiagaraComponent in the editor world), which cleanly distinguishes it from the get_/set_ Niagara siblings. The persistence detail right up front tells the agent exactly what state it produces.

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 'persists for follow-up parameter calls' clause gives clear context for when to reach for this tool (before set_niagara_component_* calls), and the owner-targeting sentence hints at the follow-up flow. It offers no explicit exclusion or named alternative, so it stops short of a full when/when-not routing.

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