create_dynamic_material_on_actor

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the mutation/safety profile is covered structurally. The description adds value by disclosing the return contract (including 'verified' and 'created' flags), but says nothing about permission requirements, whether it replaces or adds to an existing slot material, or whether repeated calls stack MIDs — meaningful gaps that contribute to the idempotentHint=false behavior.

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 tight lines with the purpose front-loaded and no filler; the Returns block is the only extra verbosity, and it earns some of its place because no output schema exists. Slightly dense but not padded.

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 simple 3-parameter creation tool with full schema coverage, the description covers purpose and return shape (filling the gap left by the missing output schema). However, it omits the usage conditions and side effects that an agent needs to invoke it confidently, so it is adequate rather than complete.

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%, so the schema already documents actor_name, element_index (with default) and parent_material_path. The description's 'Returns' block echoes some of those names (parent_material_path, element_index) without adding format or constraint detail beyond the schema, 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?

The description states a specific verb and resource ('Create a component-owned Material Instance Dynamic on a scene actor'), which is more specific than the bare tool name and clarifies the MID is component-owned rather than a standalone asset. It does not explicitly differentiate itself from close siblings like create_material_instance_dynamic or create_material_instance, so it stops short of a 5.

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 statement of when to use this tool versus alternatives such as create_material_instance_dynamic or set_actor_material, and no prerequisites (e.g., the target actor/component must exist). The 'component-owned ... on a scene actor' phrasing implies the editing context but offers no exclusions or guidance.

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