create_material_expression

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

No annotations are provided, so the description carries the full burden. It states the action but does not disclose side effects, whether a material must already exist, behavior on invalid paths, or any error conditions. For a mutating operation, this is a significant gap.

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, clear sentence that front-loads the action and resource, followed by useful examples. No wasted words.

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 node-adding tool, the description is minimally sufficient, but it lacks context about how this fits into a broader workflow (e.g., adding a node is separate from connecting it). No output schema or annotation support increases the burden, but the operation itself is straightforward.

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?

The schema already provides descriptions for all parameters (100% coverage), so the baseline is 3. The description adds value by giving concrete examples of valid expression_class values, but does not elaborate on x/y placement semantics beyond the schema.

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 uses a specific verb ('Add') and resource ('expression node to a material's graph'), with concrete examples (TextureSample, Multiply, Constant3Vector). This clearly distinguishes it from sibling tools like create_material or connect_material_expressions.

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?

The purpose implies usage (add a node to a material graph), but no explicit guidance is given about when to use this tool versus alternatives like add_graph_node or connect_material_expressions. The description does not mention exclusions or prerequisites.

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