render_element_add

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

Annotations already mark this as a mutating/destructive operation (destructiveHint=true, readOnlyHint=false), and the description adds a non-obvious behavioral warning that certain elements are silently skipped without an explicit output path. This is useful, non-obvious behavior that the annotations alone would 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?

The description is compact, lists the full range of supported elements, and front-loads the critical silent-skip warning. The bilingual duplication is slightly repetitive but not bloated.

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 two-parameter tool with no output schema, the description covers the core call pattern, the accepted values, and the key pitfall around output paths. It is sufficient for an agent to invoke the tool correctly, though it does not exhaustively document every possible render element value beyond the examples and 'etc.'

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 schema already documents element and output. The description adds meaning by enumerating the accepted render-element names and explaining why the optional output parameter matters specifically for ZDepth/Normal, going beyond the schema's basic descriptions.

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 clearly states the tool adds a render element and enumerates the supported element types (zdepth, normal, objectid, etc.), so an agent knows exactly what operation and resource are involved. It does not explicitly contrast itself with sibling tools like render_element_remove or render_element_set_output, so it stops short of full sibling differentiation.

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 description provides a valuable usage condition: ZDepth, Normal, and similar elements need an explicit output path or the render silently skips them, and the output parameter is the way to set it. However, it does not explicitly say when to prefer this tool over alternatives such as render_element_set_output for adjusting output paths later, leaving part of the decision implicit.

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