Set type on a text layer

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

The destructiveHint annotation already signals mutation, and the description adds meaningful behavioral context by clarifying that only named properties are overwritten and others are preserved. It doesn't describe reversibility or what exactly gets destroyed, but the partial-update disclosure is valuable beyond the annotation.

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?

Three sentences with no filler: the first gives scope, the second defines update semantics, and the third supplies routing rationale. The most important caveat ('Only what you name is changed') is front-loaded right after the scope.

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, the description covers what to change and when to prefer an alternative. Minor gaps remain: it doesn't describe return behavior, failure modes, or the autoResize parameter, but the schema compensates for the parameter details and the annotations cover the destructive nature.

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 56%, so the schema carries some parameter descriptions. The description adds value by grouping the parameters into readable categories (font, size, line height, etc.) and by explaining that each named parameter is applied independently. It does not mention autoResize, leaving one parameter semantically under-covered.

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 names the exact operation (set type on a text layer) and enumerates the specific attributes it affects: font, size, line height, letter spacing, alignment and colour. It also differentiates itself from the most confusable sibling, figma_apply_style, by framing hard-coded values as a fallback rather than a substitute for named styles.

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 last sentence gives explicit routing: prefer figma_apply_style when a text style exists, with a concrete reason (a named style survives redesigns). The phrase 'Only what you name is changed' also tells the agent this is a targeted partial update, not a full style reset.

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