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MatthewDailey

Figma MCP Server

post_comment

Add comments to specific elements in Figma files to provide feedback, ask questions, or mark design areas for review.

Instructions

Post a comment on a node in a Figma file

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
file_keyYesThe key of the Figma file
node_idNoThe ID of the node to comment on. Node ids have the format `<number>:<number>`
messageYesThe comment message
xYesThe x coordinate of the comment pin
yYesThe y coordinate of the comment pin

Implementation Reference

  • Primary handler function for the post_comment tool. It calls the Figma API helper and formats the response as MCP CallToolResult.
    async function doPostComment(
      fileKey: string,
      message: string,
      x: number,
      y: number,
      nodeId?: string
    ): Promise<CallToolResult> {
      const data = await postComment(fileKey, message, x, y, nodeId);
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(data, null, 2),
          },
        ],
      };
    }
  • Tool definition for post_comment, including name, description, and detailed input schema.
    const POST_COMMENT: Tool = {
      name: "post_comment",
      description: "Post a comment on a node in a Figma file",
      inputSchema: {
        type: "object",
        properties: {
          file_key: {
            type: "string",
            description: "The key of the Figma file",
          },
          node_id: {
            type: "string",
            description:
              "The ID of the node to comment on. Node ids have the format `<number>:<number>`",
          },
          message: {
            type: "string",
            description: "The comment message",
          },
          x: {
            type: "number",
            description: "The x coordinate of the comment pin",
          },
          y: {
            type: "number",
            description: "The y coordinate of the comment pin",
          },
        },
        required: ["file_key", "message", "x", "y"],
      },
    };
  • index.ts:138-140 (registration)
    Registration of the POST_COMMENT tool in the listTools request handler.
    server.setRequestHandler(ListToolsRequestSchema, async () => ({
      tools: [ADD_FIGMA_FILE, VIEW_NODE, READ_COMMENTS, POST_COMMENT, REPLY_TO_COMMENT],
    }));
  • Dispatch handler in CallToolRequestSchema that routes post_comment requests to the doPostComment function.
    if (request.params.name === "post_comment") {
      const input = request.params.arguments as {
        file_key: string;
        node_id?: string;
        message: string;
        x: number;
        y: number;
      };
      return doPostComment(input.file_key, input.message, input.x, input.y, input.node_id);
    }
  • Core helper function that performs the actual HTTP POST request to the Figma Comments API.
    export async function postComment(
      fileKey: string,
      message: string,
      x: number,
      y: number,
      nodeId?: string
    ) {
      const response = await axios.post(
        `https://api.figma.com/v1/files/${fileKey}/comments`,
        {
          message,
          client_meta: { node_offset: { x, y }, node_id: nodeId },
        },
        {
          headers: {
            "X-FIGMA-TOKEN": getFigmaApiKey(),
            "Content-Type": "application/json",
          },
        }
      );
      return response.data;
    }

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

C2.9/5.0
Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the action ('Post a comment') but fails to describe critical behaviors such as whether this requires specific permissions, if comments are publicly visible or private, rate limits, error handling, or what happens on success (e.g., comment ID returned). For a mutation tool with zero annotation coverage, this is a significant gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, efficient sentence that directly states the tool's purpose without unnecessary words. It is appropriately sized and front-loaded, with every word earning its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity of a mutation tool (posting comments) with no annotations and no output schema, the description is incomplete. It lacks information on behavioral traits (e.g., permissions, visibility), usage context, and expected outcomes. The high schema coverage helps with parameters, but overall context is insufficient for effective tool selection and invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the input schema already documents all 5 parameters thoroughly. The description adds no additional meaning beyond what's in the schema (e.g., it doesn't explain parameter interactions or provide examples). According to the rules, baseline is 3 when schema coverage is high (>80%) and no param info is in the description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Post a comment') and the target ('on a node in a Figma file'), providing a specific verb+resource combination. However, it doesn't differentiate from sibling tools like 'reply_to_comment' or 'read_comments', which would require explicit comparison to achieve a score of 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives like 'reply_to_comment' or 'read_comments', nor does it mention prerequisites such as file access permissions or comment visibility. It only states what the tool does without contextual usage instructions.

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