figma_append_to_slot

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

With no annotations, the description carries the full burden and does disclose the important side effects: passing fileKey does not change the active file or target lock, and Cloud Mode rejects fileKey outright. It also flags which node kinds cannot be appended. It stops short of describing what the call returns or what happens to the appended node's position/layout, which matters for a 9-param mutation.

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?

Front-loaded with the core action, then the constraint, then a clearly headed MULTI-FILE paragraph. The fileKey sentence largely duplicates the schema's own description verbatim, which is the only real waste.

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 9-parameter, zero-required, no-output-schema tool, the description supplies the missing decision logic: two creation modes, the sibling it replaces, exclusions, and the multi-file targeting rule. No return-value documentation is needed since no output schema exists and the tool's effect is the appended content itself.

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, but the description adds real semantics by framing sourceNodeId and nodeType as two mutually exclusive modes and calling out that clone defaults to true (false moves rather than copies). It does not state that slotId or the instanceId+slotName pair is the required addressing combination, which is the main unanswered parameter question.

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: 'Add content to a slot on a component instance', and immediately explains the two underlying mechanisms (clone sourceNodeId or create via nodeType). It explicitly distinguishes itself from figma_set_instance_properties and cites the negative cases (widgets, stickies, raw ComponentNodes), so an agent can separate it from siblings without opening the schema.

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?

Gives explicit routing: SLOT content cannot be set via figma_set_instance_properties, use this tool instead, and names figma_list_open_files for fileKey sourcing. It also states exclusions (widgets, stickies, raw ComponentNodes) and cross-references figma_get_slots for slotId, leaving little to inference.

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