Create slot

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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true), so the description does not need to restate safety. It adds genuine behavioral context beyond annotations: editor availability scoping (Design; unverified FigJam, Slides) and the validation rule that Figma refuses a grid layout on a slot. It stops short of describing return shape or failure behavior, so a 3 is appropriate given annotations carry the safety burden.

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-loads purpose, then preconditions, cross-tool routing, and environment scope in a dense sequence where every sentence carries new information. No filler or restatement of the name.

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 with a nested sizing object and no output schema, the description covers purpose, valid input shape, layout constraint, follow-up tools, and editor scope. It omits anything about default sizing/layout behavior or what the call returns, minor gaps rather than blocking ones.

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 moderately high (75%), so the baseline is 3, but the description adds meaning beyond the schema: the layout constraint ('Figma refuses a grid on a slot') sharpens an enum the schema only labels 'Auto-layout direction', and the componentId constraint ('not a set') adds an input rule the schema does not state. Width, height, and sizing are left entirely to 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?

States a specific verb and resource ('Add a slot to a component') and immediately defines what a slot actually is (a frame each instance fills with its own layers, plus the SLOT property). This is enough for an agent to tell it apart from sibling node-creation tools like figma_create_frame or figma_convert_to_component without opening a 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 preconditions and exclusions: 'Pass a component or one variant, not a set', slot filling happens via parentId in an instance, figma_reset_slot empties it, and figma_set_instance_properties cannot set a slot. This is concrete when/when-not guidance with named alternatives.

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