Set variable mode

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

Adds substantial behavior beyond annotations: idempotentHint is declared but the description explains inheritance semantics, that clear:true removes the pin, that per-item results are returned and one item failing does not fail the whole call, and the editor-support caveat (Design yes; FigJam/Slides unverified). This is rich, non-redundant behavioral context.

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 purpose, then inheritance rationale, then the clear escape hatch, then return shape and editor support. Dense but every clause carries load; no filler.

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 mutation tool with no output schema and no annotations covering return format, the description supplies return shape, failure semantics, inheritance rules, the clear path, and platform caveats. Nothing needed to call it correctly is missing.

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 71% and the description adds meaning beyond it: collection may be given by id or name, mode by name or id, and clear:true removes the pin. The idempotencyKey retry semantics are left to the schema, so it does not fully cover the 7 params, but the description meaningfully compensates.

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?

Names a specific verb (pin/set a mode) and resource (nodes in a variable mode), and the opening sentence distinguishes it from the sibling family: figma_add_variable_mode creates modes, this one assigns an existing mode to nodes. An agent can route correctly 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?

Explains the key context: without it every node uses the collection's default mode, so a Dark mode can exist but never render. This is a clear when-to-use signal. It lacks explicit named alternatives (e.g. 'to remove the pin use clear:true' is covered, but no pointer to sibling tools), so 4 not 5.

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