create_material_instance_dynamic

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the agent knows this mutates state and creates a new object each call. The description adds real value with 'runtime-only,' implying a transient, non-persisted object, but it omits lifetime/ownership concerns (e.g., that the MID must be held by a reference to avoid garbage collection), which matter for a non-idempotent creation tool.

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?

Two compact lines, verb and scope front-loaded, and the return-field list is placed second. Since no output schema exists, the Returns line earns its place rather than repeating structured data.

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?

The description compensates for the missing output schema by enumerating return fields, which is helpful. However, for a non-idempotent creation tool sitting among many material-creation siblings, it lacks sibling differentiation and any note on object lifetime or persistence.

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 both parameters are already documented, including the default auto-generated name. The description adds no parameter detail beyond the schema, so the baseline of 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 and resource plus a meaningful qualifier: 'runtime-only Material Instance Dynamic (MID) from a parent material.' The 'runtime-only' scope helps separate it from asset-creating siblings, but it never names create_material_instance or create_dynamic_material_on_actor, so the agent must infer the distinction.

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?

There is no when-to-use guidance. With siblings like create_material_instance, create_material_instance_constant, and create_dynamic_material_on_actor in the same namespace, the description should say when a runtime-only MID is the right choice (e.g., per-actor parameter tweaks that shouldn't be saved as an asset). Nothing is stated.

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