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set_mid_texture_param

DestructiveIdempotent

Set a texture parameter override on a transient Material Instance Dynamic by MID path. Changes apply immediately, are not saved, and only global texture parameter names are accepted.

Instructions

Set a texture parameter override on a transient Material Instance Dynamic (MID), found by object path or name as create_material_instance_dynamic or create_dynamic_material_on_actor return it; it takes effect at once and is never saved. parameter_name must be a global texture parameter of the MID's material (as get_mid_all_params lists it); any other name is refused and nothing is written. set is the read-back of the new texture. Scalars and vectors: set_mid_scalar_param, set_mid_vector_param.

Returns: { mid_path, parameter_name, old_texture_path, new_texture_path, requested_texture_path, set }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
mid_pathYesObject path of the MID (transient or component-owned full path)
texture_pathYesContent path to the texture to assign
parameter_nameYesName of a texture parameter of the MID's material

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.2.2
    • changedInput schema / properties / parameter_name / description
      Previous value: -"Name of the texture parameter"New value: +"Name of a texture parameter of the MID's material"
  2. First observedv1.1.0

TDQS

A4.3/5.0
Behavior4/5

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

Goes beyond the annotations by disclosing that the change takes effect immediately and is never saved (transient), and that an invalid parameter name is refused and nothing is written. These are real behavioral traits not derivable from readOnlyHint/destructiveHint/idempotentHint alone.

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 scoping, then validation, then sibling routing, then the return shape. It is dense but every sentence carries information; only minor tightening is possible.

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

Completeness4/5

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

With no output schema, the description correctly enumerates the returned fields (mid_path, parameter_name, old/new/requested texture paths, set). Combined with transience and validation semantics, an agent has enough to call it correctly; only auth/permission context is absent.

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

Parameters4/5

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

Schema coverage is 100%, so baseline is 3, but the description adds meaning: parameter_name must be a global texture parameter as get_mid_all_params lists it (with a documented refusal path), and mid_path is the path returned by the create_* functions. This compensates usefully rather than just restating field docs.

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 specific verb (Set) plus resource (texture parameter override on a transient MID), and explicitly distinguishes the texture case from the scalar/vector siblings set_mid_scalar_param and set_mid_vector_param. An agent can identify exactly what this does 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.

Usage Guidelines4/5

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

It names the alternatives (scalars/vectors route to the other two set_mid_* tools) and states the prerequisite that the MID must come from create_material_instance_dynamic/create_dynamic_material_on_actor and that the parameter must be listed by get_mid_all_params. That is clear context, though there is no explicit 'do not use when' exclusion for persistent (non-transient) material instances.

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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