content_create_material_instance

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

No annotations are supplied, so the description carries the full disclosure burden. It does contribute real behavioral facts: overrides are validated and applied atomically, so a failed override should not leave a half-configured asset. It omits other mutation-critical behavior such as what happens if relativePath already exists, whether the asset is saved/registered immediately, and what errors surface.

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?

A single sentence with the verb and resource front-loaded and no filler. Every clause (source material, validation, atomicity) carries information an agent needs.

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 3-parameter creation tool with 100% schema coverage and an output schema (so return values needn't be described), the description covers source, destination semantics, and failure atomicity. The remaining gap is overwrite behavior and sibling routing, which is a usage-guideline issue rather than incompleteness.

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 the baseline is 3, but the description adds meaning the schema does not: overrides are keyed by public parameter names, are validated, and are applied atomically as a set. That tells the agent failures are all-or-nothing rather than per-parameter, which is genuine added value.

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 ("Creates a MaterialInstance asset") plus its source ("from a live surface material") and its effect ("applies validated parameter overrides atomically"). This is enough to distinguish it from content_create_material and content_set_material_instance_parameter, though it never names those siblings to make the distinction explicit.

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 guidance on when to choose this tool versus content_create_material (plain material creation) or content_set_material_instance_parameter (updating an existing instance). The phrase "from a live surface material" implies baseMaterialId must reference an existing material, but the agent must infer that rather than being told.

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