create_instance_from_set_key

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

With no annotations, the description carries the full burden. It usefully discloses that the default variant is created and how placement behaves in auto-layout vs freeform parents, but it says nothing about permissions, error behavior for invalid/missing keys, mutability/reversibility, or what ignoreAutoLayout does. Moderate but incomplete for a mutation tool.

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 tightly packed sentences: purpose and target first, then the placement rules. Zero filler and the most decision-relevant information is front-loaded.

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 an 8-parameter mutation tool with no annotations and no output schema, the description covers the central placement decision adequately but omits prerequisites, failure modes, and any sense of the returned instance, leaving meaningful gaps for correct invocation.

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 only 25%, so the description must compensate, and it does explain the key parameter interactions: parentNodeId + index for auto-layout and x/y only for freeform. That adds genuine meaning for four parameters the schema leaves bare, though componentSetKey format, ignoreAutoLayout, and the layoutSizing enums remain unexplained.

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 gives a specific verb and resource ('Create an instance from a library component set key') plus the target context ('inside the target frame/parent'), and the '(default variant)' qualifier implicitly separates it from create_instance_from_component_key and create_instance_from_instance. It doesn't explicitly name those siblings, so an agent must infer the distinction, but the purpose is unambiguous.

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 second sentence provides real conditional guidance: use parentNodeId + index for auto-layout stacks, omit x/y unless the parent is freeform. However, it offers no help choosing between this tool and the many sibling instance-creation tools, and states no prerequisites (e.g., the set must already be imported).

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