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by CarlxsMG
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set_niagara_mesh_renderer_mesh

DestructiveIdempotent

Assign a static mesh to a Niagara Mesh renderer's Meshes[] slot, fixing empty renderers that draw nothing. Loads the mesh asset, grows the array if needed, then compiles and saves the system.

Instructions

Assign a static mesh into a Niagara Mesh renderer's Meshes[] slot. Resolves (or grows the array to) the slot index, loads the UStaticMesh, and sets the slot's inner .Mesh via reflection on the FNiagaraMeshRendererMeshProperties element. Then requests a system compile and saves. add_niagara_renderer type=Mesh leaves Meshes empty (renders nothing); this is the command that makes a Mesh renderer actually draw. Idempotent: re-assigning the same mesh to the same slot does not grow the array.

Returns: { system_path, emitter_name, renderer_index, renderer_class, slot, mesh_path, mesh_count, already_assigned: bool, save_error? }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
slotYesOptional 0-based slot index into Meshes[] (default 0). The array is grown with default elements up to this index if needed.
mesh_pathYesAsset path of the UStaticMesh to assign (e.g. "/Engine/BasicShapes/Cube").
system_pathYesAsset path of the Niagara System.
emitter_nameYesName of the emitter handle.
renderer_indexYes0-based index of the Mesh renderer (use get_niagara_emitter_renderers).

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.2.0
    • changedInput schema / required
      Previous value: -[
-  "emitter_name",
-  "renderer_index",
-  "mesh_path",
-  "slot"
-]New value: +[
+  "system_path",
+  "emitter_name",
+  "renderer_index",
+  "mesh_path",
+  "slot"
+]
  2. First observedv1.1.0

TDQS

A4.6/5.0
Behavior5/5

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

Annotations cover the safety profile (readOnly=false, destructive=true, idempotent=true), and the description adds substantial behavior beyond them: it grows the array, loads the UStaticMesh, sets the inner .Mesh via reflection on FNiagaraMeshRendererMeshProperties, then requests a system compile and saves. The idempotency mechanic and the exact return payload are also disclosed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and mechanism, followed by the sibling-routing rationale and idempotency note. Dense but each sentence carries information; the inline return-shape listing is slightly verbose though useful given no output schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 5-required-param mutation tool with no output schema, the description supplies the operational sequence (load, reflect-set, compile, save), the idempotency guarantee, and the return payload shape, leaving no critical gap for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all five parameters are already documented (slot default/growth, mesh_path example, renderer_index with a discovery tool hint). The description's mention of resolving/growing the slot index reiterates what the schema already states, adding little beyond the schema baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a precise verb+resource+location: 'Assign a static mesh into a Niagara Mesh renderer's Meshes[] slot.' It is clearly distinguishable from adjacent tools like add_niagara_renderer, set_niagara_renderer_material, and set_niagara_renderer_properties without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly defines the usage context and why the tool exists: add_niagara_renderer type=Mesh leaves Meshes empty and renders nothing, so this is the command that makes a Mesh renderer draw. The renderer_index schema also routes to get_niagara_emitter_renderers as the discovery step.

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

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