figma_set_image_fill

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

With no annotations, the description carries the full burden. It usefully discloses the data pipeline (base64 decoded in the browser bridge, passed as raw bytes) and the plugin prerequisite, but says nothing about whether existing fills are replaced or appended, size limits, or failure modes for a mutation tool.

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 short sentences, front-loaded with the action, then the parameter detail, then the prerequisite. Very little waste; the only redundancy is restating the base64/JPEG/PNG fact already in the schema.

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 3-parameter mutation tool with no annotations and no output schema, the definition covers the plugin requirement and encoding path but omits what happens to pre-existing fills, what the call returns, and any constraints on image size or node type.

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 the baseline is 3. The description reinforces the imageData encoding and format, which slightly overlaps the schema, but adds the extra meaning that the string is decoded in the bridge and reaches the plugin as raw bytes. scaleMode is not mentioned at all.

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 opens with a specific verb and resource: 'Set an image fill on one or more Figma nodes.' That is clearly distinguishable from a plain fills tool, but it never names the sibling it differs from (e.g. figma_set_fills), so differentiation is left implicit.

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 only usage condition given is 'Requires Desktop Bridge plugin', which is a genuine prerequisite. There is no guidance on when to prefer this over figma_set_fills, figma_set_strokes, or an execute call, and no exclusions or limits are stated.

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