create_component_instance

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It does not mention that this is a mutation operation, any permission requirements, the return value, or what happens if the component is not found. It only notes the limitation that published components 'only work' when using componentKey, which is a partial disclosure. This is insufficient for a tool that creates/modifies document structure.

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 two sentences, both informative and directly relevant. The first sentence states the purpose, and the second provides the key distinction for parameter selection. No wasted words, front-loaded with the core action.

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 tool with 5 parameters, 2 required, and no output schema or annotations, the description covers the main usage modes but omits important context such as what the tool returns (e.g., the created instance node), how placement works (x/y vs parentId), and any side effects. It is adequate for basic selection but not fully complete for an agent to understand the full consequences of invoking the tool.

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 baseline is 3. The description adds value by clarifying the distinction between the two component identifier parameters and reinforcing the correct usage for each. It supplements the schema descriptions by tying the two parameters together and providing a decision framework, which goes slightly beyond the structured fields.

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's function: 'Create an instance of a component in Figma.' It uses a specific verb and resource, and distinguishes between local and published library components, which differentiates it from sibling tools like create_rectangle or create_text. The two usage modes are explicitly described.

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 explicit guidance on when to use componentId vs componentKey based on whether the component is local or from a published library. It also mentions the source fields (id vs publishedKey) from get_local_components. While it doesn't explicitly name alternative tools, the usage context is clear and actionable.

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