Create text style

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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, so the safety profile is covered. Beyond that, the description discloses real behavioral traits: the style is 'local' (not a shared/published library style), only Design editors can run it, and lineHeight/letterSpacing now reject bare JSON numbers — a concrete failure mode an agent would otherwise hit. It stays silent on collision behavior when a style of the same name already exists.

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 opening fragment 'A local TEXT style.' is not front-loaded with the action the tool performs, and the middle sentences are a dense em-dash run-on mixing formatting rules with option names. Content is relevant but not prioritized: the string-vs-number trap deserves the lead position rather than following an incomplete noun phrase. Mid-weight and functional but not tight.

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 13-parameter create tool with no output schema and 77% schema coverage, the description covers the formatting param traps, the update path and the editor restriction reasonably well. The notable gap is the return value: since no output schema exists and the style must subsequently be applied via figma_apply_style_to_node, the agent is never told that an id/handle comes back to chain with. The idempotency key's retry semantics are left entirely to the schema.

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 77%, near the high band, so the schema already carries most parameter meaning — including the 'A string, not a number' warnings for lineHeight and letterSpacing that the description largely restates. The description adds a cross-reference to figma_set_text_properties and a use-case example ('upper for labels') but no new syntax or constraint information. Baseline 3 is appropriate for near-high coverage.

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 text establishes a specific resource (a local TEXT style) and the title supplies the create verb; the phrase 'A local TEXT style.' alone is elliptical but unambiguous in combination. It distinguishes itself from siblings by pointing at figma_update_style for later in-place changes, separating create from update. It does not contrast with figma_create_paint_style, figma_create_effect_style or figma_create_grid_style, which are the nearest siblings.

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?

'Change it later in place with figma_update_style' names one alternative and the condition selecting it, and 'Editors: Design only' states an environment restriction. However, there is no guidance on when to define a reusable style versus applying formatting directly via figma_set_text_properties, nor on when to publish to a library versus staying local. Usage is implied rather than explicit for the main create-vs-set decision.

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