create_material_instance_constant

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

Annotations already declare idempotentHint, non-destructive, and readOnly=false, so the safety profile is covered. The description adds real value on top: it explains idempotent behavior concretely ('an existing asset comes back with already_existed=true') and clarifies the parent stays untouched and updatable, which is behavioral context the annotations do not convey.

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?

Front-loaded with the core action and target, followed by rationale, idempotency, sibling differentiation, and return shape. Every sentence carries information, though the description runs slightly long for a three-parameter tool.

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?

No output schema exists, but the description inlines the full return shape (including save_error), covers the path default, parent handling, and idempotency. For a creation tool of this complexity, it is complete enough for an agent to call it 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%, so name, package_path, and parent_material_path are already documented in the schema. The description reinforces the path/parent concept but adds no syntax or format detail beyond what the schema provides, 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?

States a specific verb and resource ('Create a material instance (MIC) asset under a /Game path') and explicitly distinguishes it from the lookalike sibling create_material_instance by noting that the other tool addresses the target by folder plus name rather than a full path. An agent can tell the two apart without opening a schema.

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?

Gives a clear use case ('the right way to re-skin a vendor or engine material') and names the alternative create_material_instance along with the condition that selects it (full path vs. folder plus name). It lacks an explicit when-not-to-use statement, but the routing guidance is unambiguous.

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