Linear MCP Server

Instructions

Implementation Reference

• src/tools/handlers/issue-handlers.ts:156-169 (handler)

  The core handler function that executes the linear_assignIssue tool. Validates input with isAssignIssueArgs type guard and delegates to LinearService.assignIssue.

  export function handleAssignIssue(linearService: LinearService) {
    return async (args: unknown) => {
      try {
        if (!isAssignIssueArgs(args)) {
          throw new Error("Invalid arguments for assignIssue");
        }
        
        return await linearService.assignIssue(args.issueId, args.assigneeId);
      } catch (error) {
        logError("Error assigning issue", error);
        throw error;
      }
    };
  }

• src/tools/definitions/issue-tools.ts:456-489 (schema)

  The MCP tool definition (schema) for linear_assignIssue, including input and output schemas.

  export const assignIssueToolDefinition: MCPToolDefinition = {
    name: "linear_assignIssue",
    description: "Assign an issue to a user",
    input_schema: {
      type: "object",
      properties: {
        issueId: {
          type: "string",
          description: "ID or identifier of the issue to assign (e.g., ABC-123)",
        },
        assigneeId: {
          type: "string",
          description: "ID of the user to assign the issue to, or null to unassign",
        },
      },
      required: ["issueId", "assigneeId"],
    },
    output_schema: {
      type: "object",
      properties: {
        success: { type: "boolean" },
        issue: {
          type: "object",
          properties: {
            id: { type: "string" },
            identifier: { type: "string" },
            title: { type: "string" },
            assignee: { type: "object" },
            url: { type: "string" }
          }
        }
      }
    }
  };

• src/tools/handlers/index.ts:88-88 (registration)

  Registration of the linear_assignIssue tool handler in the tool handlers registry.

  linear_assignIssue: handleAssignIssue(linearService),

• src/tools/type-guards.ts:252-264 (helper)

  Type guard function used in the handler to validate arguments for linear_assignIssue.

  export function isAssignIssueArgs(args: unknown): args is {
    issueId: string;
    assigneeId: string;
  } {
    return (
      typeof args === "object" &&
      args !== null &&
      "issueId" in args &&
      typeof (args as { issueId: string }).issueId === "string" &&
      "assigneeId" in args &&
      typeof (args as { assigneeId: string }).assigneeId === "string"
    );
  }